diff --git a/packages/async/async.v0.13.0/opam b/packages/async/async.v0.13.0/opam
index 6d2e4aad6f6..120cfc194c8 100644
--- a/packages/async/async.v0.13.0/opam
+++ b/packages/async/async.v0.13.0/opam
@@ -27,3 +27,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async-v0.13.0.tar.gz"
+  checksum: "md5=fbfc7059179bc9ddd5dc1411e7d2e815"
+}
diff --git a/packages/async/async.v0.13.0/url b/packages/async/async.v0.13.0/url
deleted file mode 100644
index 7b44a1ae169..00000000000
--- a/packages/async/async.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async-v0.13.0.tar.gz"
-checksum: "fbfc7059179bc9ddd5dc1411e7d2e815"
diff --git a/packages/async_durable/async_durable.v0.13.0/opam b/packages/async_durable/async_durable.v0.13.0/opam
index 9e79ee62376..812698ca954 100644
--- a/packages/async_durable/async_durable.v0.13.0/opam
+++ b/packages/async_durable/async_durable.v0.13.0/opam
@@ -22,3 +22,7 @@ description: "
 \\ Async_durable helps recover from errors when
 connections can be easily be recreated.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_durable-v0.13.0.tar.gz"
+  checksum: "md5=3be4117bfc56ac5d4c6692a4d2854238"
+}
diff --git a/packages/async_durable/async_durable.v0.13.0/url b/packages/async_durable/async_durable.v0.13.0/url
deleted file mode 100644
index 9ebfd3afbe7..00000000000
--- a/packages/async_durable/async_durable.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_durable-v0.13.0.tar.gz"
-checksum: "3be4117bfc56ac5d4c6692a4d2854238"
diff --git a/packages/async_extra/async_extra.v0.13.0/opam b/packages/async_extra/async_extra.v0.13.0/opam
index 142307b362f..298b5cd3996 100644
--- a/packages/async_extra/async_extra.v0.13.0/opam
+++ b/packages/async_extra/async_extra.v0.13.0/opam
@@ -23,3 +23,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_extra-v0.13.0.tar.gz"
+  checksum: "md5=a1f6004fbac5c281c2785571595381dd"
+}
diff --git a/packages/async_extra/async_extra.v0.13.0/url b/packages/async_extra/async_extra.v0.13.0/url
deleted file mode 100644
index ce5694f7694..00000000000
--- a/packages/async_extra/async_extra.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_extra-v0.13.0.tar.gz"
-checksum: "a1f6004fbac5c281c2785571595381dd"
diff --git a/packages/async_find/async_find.v0.13.0/opam b/packages/async_find/async_find.v0.13.0/opam
index 612f558c662..cce23f81e6a 100644
--- a/packages/async_find/async_find.v0.13.0/opam
+++ b/packages/async_find/async_find.v0.13.0/opam
@@ -19,3 +19,7 @@ depends: [
 synopsis: "Directory traversal with Async"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_find-v0.13.0.tar.gz"
+  checksum: "md5=cfef781aeedf8ddbf2a7a02cda817c0a"
+}
diff --git a/packages/async_find/async_find.v0.13.0/url b/packages/async_find/async_find.v0.13.0/url
deleted file mode 100644
index 99ad45452c1..00000000000
--- a/packages/async_find/async_find.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_find-v0.13.0.tar.gz"
-checksum: "cfef781aeedf8ddbf2a7a02cda817c0a"
diff --git a/packages/async_inotify/async_inotify.v0.13.0/opam b/packages/async_inotify/async_inotify.v0.13.0/opam
index 3a57290b1d7..4e4fcc2b86e 100644
--- a/packages/async_inotify/async_inotify.v0.13.0/opam
+++ b/packages/async_inotify/async_inotify.v0.13.0/opam
@@ -21,3 +21,7 @@ depends: [
 synopsis: "Async wrapper for inotify"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_inotify-v0.13.0.tar.gz"
+  checksum: "md5=c7e91a9ef2f1c79dc41e978224a663fc"
+}
diff --git a/packages/async_inotify/async_inotify.v0.13.0/url b/packages/async_inotify/async_inotify.v0.13.0/url
deleted file mode 100644
index 9339494c755..00000000000
--- a/packages/async_inotify/async_inotify.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_inotify-v0.13.0.tar.gz"
-checksum: "c7e91a9ef2f1c79dc41e978224a663fc"
diff --git a/packages/async_interactive/async_interactive.v0.13.0/opam b/packages/async_interactive/async_interactive.v0.13.0/opam
index cc8fcfdea11..affa204659d 100644
--- a/packages/async_interactive/async_interactive.v0.13.0/opam
+++ b/packages/async_interactive/async_interactive.v0.13.0/opam
@@ -19,3 +19,7 @@ depends: [
 synopsis: "Utilities for building simple command-line based user interfaces"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_interactive-v0.13.0.tar.gz"
+  checksum: "md5=fa6d1cd5a5b83ec2e9cc76beafb54c1a"
+}
diff --git a/packages/async_interactive/async_interactive.v0.13.0/url b/packages/async_interactive/async_interactive.v0.13.0/url
deleted file mode 100644
index ef7c1bd0d09..00000000000
--- a/packages/async_interactive/async_interactive.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_interactive-v0.13.0.tar.gz"
-checksum: "fa6d1cd5a5b83ec2e9cc76beafb54c1a"
diff --git a/packages/async_js/async_js.v0.13.0/opam b/packages/async_js/async_js.v0.13.0/opam
index 5a1c219d5d5..021d356e111 100644
--- a/packages/async_js/async_js.v0.13.0/opam
+++ b/packages/async_js/async_js.v0.13.0/opam
@@ -23,3 +23,7 @@ depends: [
 synopsis: "A small library that provide Async support for JavaScript platforms"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_js-v0.13.0.tar.gz"
+  checksum: "md5=5c58219654df50abec985a74a26d7870"
+}
diff --git a/packages/async_js/async_js.v0.13.0/url b/packages/async_js/async_js.v0.13.0/url
deleted file mode 100644
index 982f55a6459..00000000000
--- a/packages/async_js/async_js.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_js-v0.13.0.tar.gz"
-checksum: "5c58219654df50abec985a74a26d7870"
diff --git a/packages/async_kernel/async_kernel.v0.13.0/opam b/packages/async_kernel/async_kernel.v0.13.0/opam
index a352561a9cd..7fd418fbae3 100644
--- a/packages/async_kernel/async_kernel.v0.13.0/opam
+++ b/packages/async_kernel/async_kernel.v0.13.0/opam
@@ -22,3 +22,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_kernel-v0.13.0.tar.gz"
+  checksum: "md5=d12b61a3f95325a511c50964bc9c819e"
+}
diff --git a/packages/async_kernel/async_kernel.v0.13.0/url b/packages/async_kernel/async_kernel.v0.13.0/url
deleted file mode 100644
index 6de61a4ca5e..00000000000
--- a/packages/async_kernel/async_kernel.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_kernel-v0.13.0.tar.gz"
-checksum: "d12b61a3f95325a511c50964bc9c819e"
diff --git a/packages/async_rpc_kernel/async_rpc_kernel.v0.13.0/opam b/packages/async_rpc_kernel/async_rpc_kernel.v0.13.0/opam
index 9cab1572abb..b14d2865687 100644
--- a/packages/async_rpc_kernel/async_rpc_kernel.v0.13.0/opam
+++ b/packages/async_rpc_kernel/async_rpc_kernel.v0.13.0/opam
@@ -24,3 +24,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_rpc_kernel-v0.13.0.tar.gz"
+  checksum: "md5=4223feff25bdb5ee851e2fe67597b514"
+}
diff --git a/packages/async_rpc_kernel/async_rpc_kernel.v0.13.0/url b/packages/async_rpc_kernel/async_rpc_kernel.v0.13.0/url
deleted file mode 100644
index de8d859375c..00000000000
--- a/packages/async_rpc_kernel/async_rpc_kernel.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_rpc_kernel-v0.13.0.tar.gz"
-checksum: "4223feff25bdb5ee851e2fe67597b514"
diff --git a/packages/async_sendfile/async_sendfile.v0.13.0/opam b/packages/async_sendfile/async_sendfile.v0.13.0/opam
index 2e4187f38a3..b0ffdc49a0c 100644
--- a/packages/async_sendfile/async_sendfile.v0.13.0/opam
+++ b/packages/async_sendfile/async_sendfile.v0.13.0/opam
@@ -20,3 +20,7 @@ depends: [
 synopsis: "Thin wrapper around [Linux_ext.sendfile] to send full files"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_sendfile-v0.13.0.tar.gz"
+  checksum: "md5=4b2c76d996d7d89ce4531602e231377a"
+}
diff --git a/packages/async_sendfile/async_sendfile.v0.13.0/url b/packages/async_sendfile/async_sendfile.v0.13.0/url
deleted file mode 100644
index 682841647c0..00000000000
--- a/packages/async_sendfile/async_sendfile.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_sendfile-v0.13.0.tar.gz"
-checksum: "4b2c76d996d7d89ce4531602e231377a"
diff --git a/packages/async_shell/async_shell.v0.13.0/opam b/packages/async_shell/async_shell.v0.13.0/opam
index d1ce1330779..8ece38a7008 100644
--- a/packages/async_shell/async_shell.v0.13.0/opam
+++ b/packages/async_shell/async_shell.v0.13.0/opam
@@ -20,3 +20,7 @@ depends: [
 synopsis: "Shell helpers for Async"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_shell-v0.13.0.tar.gz"
+  checksum: "md5=f18ffa5ad138b31ad7b71f3942de0043"
+}
diff --git a/packages/async_shell/async_shell.v0.13.0/url b/packages/async_shell/async_shell.v0.13.0/url
deleted file mode 100644
index 317a0aafa07..00000000000
--- a/packages/async_shell/async_shell.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_shell-v0.13.0.tar.gz"
-checksum: "f18ffa5ad138b31ad7b71f3942de0043"
diff --git a/packages/async_udp/async_udp.v0.13.0/opam b/packages/async_udp/async_udp.v0.13.0/opam
index b9f9dd1f7d6..78f02f71520 100644
--- a/packages/async_udp/async_udp.v0.13.0/opam
+++ b/packages/async_udp/async_udp.v0.13.0/opam
@@ -22,3 +22,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_udp-v0.13.0.tar.gz"
+  checksum: "md5=ebc36b515617476e4a19d024add2dc4e"
+}
diff --git a/packages/async_udp/async_udp.v0.13.0/url b/packages/async_udp/async_udp.v0.13.0/url
deleted file mode 100644
index 404251b2fd7..00000000000
--- a/packages/async_udp/async_udp.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_udp-v0.13.0.tar.gz"
-checksum: "ebc36b515617476e4a19d024add2dc4e"
diff --git a/packages/async_unix/async_unix.v0.13.0/opam b/packages/async_unix/async_unix.v0.13.0/opam
index 044f35129a1..d1fe007bd99 100644
--- a/packages/async_unix/async_unix.v0.13.0/opam
+++ b/packages/async_unix/async_unix.v0.13.0/opam
@@ -24,3 +24,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_unix-v0.13.0.tar.gz"
+  checksum: "md5=1f150e28eeca17ebf3ff65641132c26d"
+}
diff --git a/packages/async_unix/async_unix.v0.13.0/url b/packages/async_unix/async_unix.v0.13.0/url
deleted file mode 100644
index b98a87f0346..00000000000
--- a/packages/async_unix/async_unix.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_unix-v0.13.0.tar.gz"
-checksum: "1f150e28eeca17ebf3ff65641132c26d"
diff --git a/packages/async_websocket/async_websocket.v0.13.0/opam b/packages/async_websocket/async_websocket.v0.13.0/opam
index e8dd74909d8..c6b49367b90 100644
--- a/packages/async_websocket/async_websocket.v0.13.0/opam
+++ b/packages/async_websocket/async_websocket.v0.13.0/opam
@@ -18,3 +18,7 @@ description: "
 This library implements both the server and client side of 
                 the websocket protocol.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_websocket-v0.13.0.tar.gz"
+  checksum: "md5=754df4fbcf767270c84f988812250541"
+}
diff --git a/packages/async_websocket/async_websocket.v0.13.0/url b/packages/async_websocket/async_websocket.v0.13.0/url
deleted file mode 100644
index a69687efc34..00000000000
--- a/packages/async_websocket/async_websocket.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/async_websocket-v0.13.0.tar.gz"
-checksum: "754df4fbcf767270c84f988812250541"
diff --git a/packages/base/base.v0.13.0/opam b/packages/base/base.v0.13.0/opam
index 41bbffd8343..ee2133652af 100644
--- a/packages/base/base.v0.13.0/opam
+++ b/packages/base/base.v0.13.0/opam
@@ -29,3 +29,7 @@ provided by companion libraries such as stdio:
 
   https://github.com/janestreet/stdio
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/base-v0.13.0.tar.gz"
+  checksum: "md5=527289dbc2c7de748f965d3caae450cb"
+}
diff --git a/packages/base/base.v0.13.0/url b/packages/base/base.v0.13.0/url
deleted file mode 100644
index 6e013ff5331..00000000000
--- a/packages/base/base.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/base-v0.13.0.tar.gz"
-checksum: "527289dbc2c7de748f965d3caae450cb"
diff --git a/packages/base_bigstring/base_bigstring.v0.13.0/opam b/packages/base_bigstring/base_bigstring.v0.13.0/opam
index 8fa8f4f53b4..60c4edfdeb1 100644
--- a/packages/base_bigstring/base_bigstring.v0.13.0/opam
+++ b/packages/base_bigstring/base_bigstring.v0.13.0/opam
@@ -19,3 +19,7 @@ synopsis: "String type based on [Bigarray], for use in I/O and C-bindings"
 description: "
 String type based on [Bigarray], for use in I/O and C-bindings.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/base_bigstring-v0.13.0.tar.gz"
+  checksum: "md5=b7fd64b0db5a02d75610b96e412da94a"
+}
diff --git a/packages/base_bigstring/base_bigstring.v0.13.0/url b/packages/base_bigstring/base_bigstring.v0.13.0/url
deleted file mode 100644
index 4452d0770ac..00000000000
--- a/packages/base_bigstring/base_bigstring.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/base_bigstring-v0.13.0.tar.gz"
-checksum: "b7fd64b0db5a02d75610b96e412da94a"
diff --git a/packages/base_quickcheck/base_quickcheck.v0.13.0/opam b/packages/base_quickcheck/base_quickcheck.v0.13.0/opam
index 2319e1356d4..786eef4ccf6 100644
--- a/packages/base_quickcheck/base_quickcheck.v0.13.0/opam
+++ b/packages/base_quickcheck/base_quickcheck.v0.13.0/opam
@@ -25,3 +25,7 @@ description: "
 Base_quickcheck provides randomized testing in the style of Haskell's Quickcheck library,
 with support for built-in types as well as types provided by Base.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/base_quickcheck-v0.13.0.tar.gz"
+  checksum: "md5=798f626f9c8836591e7b3926714ad19e"
+}
diff --git a/packages/base_quickcheck/base_quickcheck.v0.13.0/url b/packages/base_quickcheck/base_quickcheck.v0.13.0/url
deleted file mode 100644
index 1c171ae0ab3..00000000000
--- a/packages/base_quickcheck/base_quickcheck.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/base_quickcheck-v0.13.0.tar.gz"
-checksum: "798f626f9c8836591e7b3926714ad19e"
diff --git a/packages/bignum/bignum.v0.13.0/opam b/packages/bignum/bignum.v0.13.0/opam
index c5a87362334..3857f5ab216 100644
--- a/packages/bignum/bignum.v0.13.0/opam
+++ b/packages/bignum/bignum.v0.13.0/opam
@@ -23,3 +23,7 @@ depends: [
 synopsis: "Core-flavoured wrapper around zarith's arbitrary-precision rationals"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/bignum-v0.13.0.tar.gz"
+  checksum: "md5=9ac1ea985988da8e618f2b3162c8d214"
+}
diff --git a/packages/bignum/bignum.v0.13.0/url b/packages/bignum/bignum.v0.13.0/url
deleted file mode 100644
index 8b3367caeba..00000000000
--- a/packages/bignum/bignum.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/bignum-v0.13.0.tar.gz"
-checksum: "9ac1ea985988da8e618f2b3162c8d214"
diff --git a/packages/bin_prot/bin_prot.v0.13.0/opam b/packages/bin_prot/bin_prot.v0.13.0/opam
index 89fb90ec83b..dfc58ba7600 100644
--- a/packages/bin_prot/bin_prot.v0.13.0/opam
+++ b/packages/bin_prot/bin_prot.v0.13.0/opam
@@ -29,3 +29,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/bin_prot-v0.13.0.tar.gz"
+  checksum: "md5=2262cf69d1b989cdcf75055102472d74"
+}
diff --git a/packages/bin_prot/bin_prot.v0.13.0/url b/packages/bin_prot/bin_prot.v0.13.0/url
deleted file mode 100644
index 4f0bc2169ce..00000000000
--- a/packages/bin_prot/bin_prot.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/bin_prot-v0.13.0.tar.gz"
-checksum: "2262cf69d1b989cdcf75055102472d74"
diff --git a/packages/bonsai/bonsai.v0.13.0/opam b/packages/bonsai/bonsai.v0.13.0/opam
index c4630832052..f34ca03461e 100644
--- a/packages/bonsai/bonsai.v0.13.0/opam
+++ b/packages/bonsai/bonsai.v0.13.0/opam
@@ -30,3 +30,7 @@ up into roughly two modules:
 - Creating components
 - Combining components
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/bonsai-v0.13.0.tar.gz"
+  checksum: "md5=36feac848fcb4118929df74939d1d111"
+}
diff --git a/packages/bonsai/bonsai.v0.13.0/url b/packages/bonsai/bonsai.v0.13.0/url
deleted file mode 100644
index 3fc57de1240..00000000000
--- a/packages/bonsai/bonsai.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/bonsai-v0.13.0.tar.gz"
-checksum: "36feac848fcb4118929df74939d1d111"
diff --git a/packages/cinaps/cinaps.v0.13.0/opam b/packages/cinaps/cinaps.v0.13.0/opam
index d985a51c634..3d6b8ffa823 100644
--- a/packages/cinaps/cinaps.v0.13.0/opam
+++ b/packages/cinaps/cinaps.v0.13.0/opam
@@ -21,3 +21,7 @@ is based on the same idea as expectation tests. The user write some
 OCaml code inside special comments and cinaps make sure that what
 follows is what is printed by the OCaml code.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/cinaps-v0.13.0.tar.gz"
+  checksum: "md5=a08fba2769d726d877b0e653d595fd52"
+}
diff --git a/packages/cinaps/cinaps.v0.13.0/url b/packages/cinaps/cinaps.v0.13.0/url
deleted file mode 100644
index d781cb3e54e..00000000000
--- a/packages/cinaps/cinaps.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/cinaps-v0.13.0.tar.gz"
-checksum: "a08fba2769d726d877b0e653d595fd52"
diff --git a/packages/command_rpc/command_rpc.v0.13.0/opam b/packages/command_rpc/command_rpc.v0.13.0/opam
index 5962b3cb710..ab8d71c8400 100644
--- a/packages/command_rpc/command_rpc.v0.13.0/opam
+++ b/packages/command_rpc/command_rpc.v0.13.0/opam
@@ -19,3 +19,7 @@ depends: [
 synopsis: "Utilities for Versioned RPC communication with a child process over stdin and stdout"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/command_rpc-v0.13.0.tar.gz"
+  checksum: "md5=01d5fc6da802c74aa5fc8c520e980323"
+}
diff --git a/packages/command_rpc/command_rpc.v0.13.0/url b/packages/command_rpc/command_rpc.v0.13.0/url
deleted file mode 100644
index 78706659822..00000000000
--- a/packages/command_rpc/command_rpc.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/command_rpc-v0.13.0.tar.gz"
-checksum: "01d5fc6da802c74aa5fc8c520e980323"
diff --git a/packages/core/core.v0.13.0/opam b/packages/core/core.v0.13.0/opam
index df72e03268f..9cf1b0133d4 100644
--- a/packages/core/core.v0.13.0/opam
+++ b/packages/core/core.v0.13.0/opam
@@ -26,3 +26,7 @@ OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
 depexts: ["linux-headers"] {os-distribution = "alpine"}
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/core-v0.13.0.tar.gz"
+  checksum: "md5=0dedfb21e756427ea39ab4dc173d67a9"
+}
diff --git a/packages/core/core.v0.13.0/url b/packages/core/core.v0.13.0/url
deleted file mode 100644
index d4295d70f76..00000000000
--- a/packages/core/core.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/core-v0.13.0.tar.gz"
-checksum: "0dedfb21e756427ea39ab4dc173d67a9"
diff --git a/packages/core_bench/core_bench.v0.13.0/opam b/packages/core_bench/core_bench.v0.13.0/opam
index 6533c543746..e64acc07429 100644
--- a/packages/core_bench/core_bench.v0.13.0/opam
+++ b/packages/core_bench/core_bench.v0.13.0/opam
@@ -21,3 +21,7 @@ depends: [
 synopsis: "Benchmarking library"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/core_bench-v0.13.0.tar.gz"
+  checksum: "md5=310d25daf8849865cb65d350f001636a"
+}
diff --git a/packages/core_bench/core_bench.v0.13.0/url b/packages/core_bench/core_bench.v0.13.0/url
deleted file mode 100644
index cc5a9dc9d2e..00000000000
--- a/packages/core_bench/core_bench.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/core_bench-v0.13.0.tar.gz"
-checksum: "310d25daf8849865cb65d350f001636a"
diff --git a/packages/core_extended/core_extended.v0.13.0/opam b/packages/core_extended/core_extended.v0.13.0/opam
index 348dcb7bde4..aba7df65690 100644
--- a/packages/core_extended/core_extended.v0.13.0/opam
+++ b/packages/core_extended/core_extended.v0.13.0/opam
@@ -23,3 +23,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/core_extended-v0.13.0.tar.gz"
+  checksum: "md5=491a59616fecd5080bffa2f0b118bb10"
+}
diff --git a/packages/core_extended/core_extended.v0.13.0/url b/packages/core_extended/core_extended.v0.13.0/url
deleted file mode 100644
index 6b06eafb381..00000000000
--- a/packages/core_extended/core_extended.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/core_extended-v0.13.0.tar.gz"
-checksum: "491a59616fecd5080bffa2f0b118bb10"
diff --git a/packages/core_kernel/core_kernel.v0.13.0/opam b/packages/core_kernel/core_kernel.v0.13.0/opam
index f280cf3564c..a25f770d87d 100644
--- a/packages/core_kernel/core_kernel.v0.13.0/opam
+++ b/packages/core_kernel/core_kernel.v0.13.0/opam
@@ -41,3 +41,7 @@ largest industrial user of OCaml.
 
 Core_kernel is the system-independent part of Core.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/core_kernel-v0.13.0.tar.gz"
+  checksum: "md5=0fd05be8bf5eabde5080e3c40b20092b"
+}
diff --git a/packages/core_kernel/core_kernel.v0.13.0/url b/packages/core_kernel/core_kernel.v0.13.0/url
deleted file mode 100644
index 70316766d63..00000000000
--- a/packages/core_kernel/core_kernel.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/core_kernel-v0.13.0.tar.gz"
-checksum: "0fd05be8bf5eabde5080e3c40b20092b"
diff --git a/packages/core_profiler/core_profiler.v0.13.0/opam b/packages/core_profiler/core_profiler.v0.13.0/opam
index fb1c6cc99b5..b02aa460f1d 100644
--- a/packages/core_profiler/core_profiler.v0.13.0/opam
+++ b/packages/core_profiler/core_profiler.v0.13.0/opam
@@ -24,3 +24,7 @@ description: "
 Core_profiler is a library that helps you profile programs and
 estimate various costs.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/core_profiler-v0.13.0.tar.gz"
+  checksum: "md5=6da373ba39a8732ad070c65acfed29ff"
+}
diff --git a/packages/core_profiler/core_profiler.v0.13.0/url b/packages/core_profiler/core_profiler.v0.13.0/url
deleted file mode 100644
index b110e86cf93..00000000000
--- a/packages/core_profiler/core_profiler.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/core_profiler-v0.13.0.tar.gz"
-checksum: "6da373ba39a8732ad070c65acfed29ff"
diff --git a/packages/csvfields/csvfields.v0.13.0/opam b/packages/csvfields/csvfields.v0.13.0/opam
index 87e78ba6800..ac8ad5846e4 100644
--- a/packages/csvfields/csvfields.v0.13.0/opam
+++ b/packages/csvfields/csvfields.v0.13.0/opam
@@ -20,3 +20,7 @@ depends: [
 synopsis: "Runtime support for ppx_xml_conv and ppx_csv_conv"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/csvfields-v0.13.0.tar.gz"
+  checksum: "md5=5cc70c390a8dce471f86c30d5d2a490b"
+}
diff --git a/packages/csvfields/csvfields.v0.13.0/url b/packages/csvfields/csvfields.v0.13.0/url
deleted file mode 100644
index 39956a4c4c8..00000000000
--- a/packages/csvfields/csvfields.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/csvfields-v0.13.0.tar.gz"
-checksum: "5cc70c390a8dce471f86c30d5d2a490b"
diff --git a/packages/delimited_parsing/delimited_parsing.v0.13.0/opam b/packages/delimited_parsing/delimited_parsing.v0.13.0/opam
index dbc24af9aa1..dba1cece4a8 100644
--- a/packages/delimited_parsing/delimited_parsing.v0.13.0/opam
+++ b/packages/delimited_parsing/delimited_parsing.v0.13.0/opam
@@ -22,3 +22,7 @@ description: "
 Delimited_parsing parses character-separated values (such as CSV files) and fixed-width
 records.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/delimited_parsing-v0.13.0.tar.gz"
+  checksum: "md5=dd29a3b04015352543715bb3aae5405d"
+}
diff --git a/packages/delimited_parsing/delimited_parsing.v0.13.0/url b/packages/delimited_parsing/delimited_parsing.v0.13.0/url
deleted file mode 100644
index dff5d3f2e15..00000000000
--- a/packages/delimited_parsing/delimited_parsing.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/delimited_parsing-v0.13.0.tar.gz"
-checksum: "dd29a3b04015352543715bb3aae5405d"
diff --git a/packages/ecaml/ecaml.v0.13.0/opam b/packages/ecaml/ecaml.v0.13.0/opam
index 796db7a0730..7fc3fabe149 100644
--- a/packages/ecaml/ecaml.v0.13.0/opam
+++ b/packages/ecaml/ecaml.v0.13.0/opam
@@ -25,3 +25,7 @@ description: "
 Ecaml is a library for writing Emacs plugins in OCaml. It uses Emacs
 25 support for plugins to load native OCaml compiled code.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ecaml-v0.13.0.tar.gz"
+  checksum: "md5=4f58053a70cb5be73c8d98abacaab3a9"
+}
diff --git a/packages/ecaml/ecaml.v0.13.0/url b/packages/ecaml/ecaml.v0.13.0/url
deleted file mode 100644
index 1e355a9d921..00000000000
--- a/packages/ecaml/ecaml.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ecaml-v0.13.0.tar.gz"
-checksum: "4f58053a70cb5be73c8d98abacaab3a9"
diff --git a/packages/email_message/email_message.v0.13.0/opam b/packages/email_message/email_message.v0.13.0/opam
index b7d8680bb1a..eb96fbbae99 100644
--- a/packages/email_message/email_message.v0.13.0/opam
+++ b/packages/email_message/email_message.v0.13.0/opam
@@ -25,3 +25,7 @@ depends: [
 synopsis: "E-mail message parser"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/email_message-v0.13.0.tar.gz"
+  checksum: "md5=a19f9522600fbc20f16eaa5be90b1ffe"
+}
diff --git a/packages/email_message/email_message.v0.13.0/url b/packages/email_message/email_message.v0.13.0/url
deleted file mode 100644
index 7cfe508ff23..00000000000
--- a/packages/email_message/email_message.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/email_message-v0.13.0.tar.gz"
-checksum: "a19f9522600fbc20f16eaa5be90b1ffe"
diff --git a/packages/expect_test_helpers/expect_test_helpers.v0.13.0/opam b/packages/expect_test_helpers/expect_test_helpers.v0.13.0/opam
index 8fde0595acb..ccfa1ae4396 100644
--- a/packages/expect_test_helpers/expect_test_helpers.v0.13.0/opam
+++ b/packages/expect_test_helpers/expect_test_helpers.v0.13.0/opam
@@ -25,3 +25,7 @@ This library provides helper functions for writing expect tests.
 Note that this library uses Async, for helpers that don't use Async,
 look at expect_test_helpers_kernel.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/expect_test_helpers-v0.13.0.tar.gz"
+  checksum: "md5=fc3572d962d1afcbe437910e736c6b3f"
+}
diff --git a/packages/expect_test_helpers/expect_test_helpers.v0.13.0/url b/packages/expect_test_helpers/expect_test_helpers.v0.13.0/url
deleted file mode 100644
index f2655d8097f..00000000000
--- a/packages/expect_test_helpers/expect_test_helpers.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/expect_test_helpers-v0.13.0.tar.gz"
-checksum: "fc3572d962d1afcbe437910e736c6b3f"
diff --git a/packages/expect_test_helpers_kernel/expect_test_helpers_kernel.v0.13.0/opam b/packages/expect_test_helpers_kernel/expect_test_helpers_kernel.v0.13.0/opam
index df174df34d8..99f9c9d2a65 100644
--- a/packages/expect_test_helpers_kernel/expect_test_helpers_kernel.v0.13.0/opam
+++ b/packages/expect_test_helpers_kernel/expect_test_helpers_kernel.v0.13.0/opam
@@ -27,3 +27,7 @@ This library provides helper functions for writing expect tests.
 If you want helpers for writing expect tests using the Async library,
 look at expect_test_helpers.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/expect_test_helpers_kernel-v0.13.0.tar.gz"
+  checksum: "md5=5d51328bcaff8e2086fed560b1826790"
+}
diff --git a/packages/expect_test_helpers_kernel/expect_test_helpers_kernel.v0.13.0/url b/packages/expect_test_helpers_kernel/expect_test_helpers_kernel.v0.13.0/url
deleted file mode 100644
index f303cd2bfd5..00000000000
--- a/packages/expect_test_helpers_kernel/expect_test_helpers_kernel.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/expect_test_helpers_kernel-v0.13.0.tar.gz"
-checksum: "5d51328bcaff8e2086fed560b1826790"
diff --git a/packages/fieldslib/fieldslib.v0.13.0/opam b/packages/fieldslib/fieldslib.v0.13.0/opam
index 1db6f04e831..ce47ec2e658 100644
--- a/packages/fieldslib/fieldslib.v0.13.0/opam
+++ b/packages/fieldslib/fieldslib.v0.13.0/opam
@@ -21,3 +21,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/fieldslib-v0.13.0.tar.gz"
+  checksum: "md5=3ac72dc49e43416c8b6fa0897bd4838b"
+}
diff --git a/packages/fieldslib/fieldslib.v0.13.0/url b/packages/fieldslib/fieldslib.v0.13.0/url
deleted file mode 100644
index db6d2c84108..00000000000
--- a/packages/fieldslib/fieldslib.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/fieldslib-v0.13.0.tar.gz"
-checksum: "3ac72dc49e43416c8b6fa0897bd4838b"
diff --git a/packages/hardcaml/hardcaml.v0.13.0/opam b/packages/hardcaml/hardcaml.v0.13.0/opam
index 1d52f1c9506..a8e7bbf7e90 100644
--- a/packages/hardcaml/hardcaml.v0.13.0/opam
+++ b/packages/hardcaml/hardcaml.v0.13.0/opam
@@ -26,3 +26,7 @@ order functions, lists, maps etc.  A built in simulator allows designs to
 be simulated within Hardcaml.  Designs are converted to either Verilog or
 VHDL to interact with standard back end tooling.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/hardcaml-v0.13.0.tar.gz"
+  checksum: "md5=692be272e1fee9515b3b0fd16f9a1a6d"
+}
diff --git a/packages/hardcaml/hardcaml.v0.13.0/url b/packages/hardcaml/hardcaml.v0.13.0/url
deleted file mode 100644
index 4fe611e792e..00000000000
--- a/packages/hardcaml/hardcaml.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/hardcaml-v0.13.0.tar.gz"
-checksum: "692be272e1fee9515b3b0fd16f9a1a6d"
diff --git a/packages/hardcaml_waveterm/hardcaml_waveterm.v0.13.0/opam b/packages/hardcaml_waveterm/hardcaml_waveterm.v0.13.0/opam
index ff8fbcc7f45..ac430f6fd94 100644
--- a/packages/hardcaml_waveterm/hardcaml_waveterm.v0.13.0/opam
+++ b/packages/hardcaml_waveterm/hardcaml_waveterm.v0.13.0/opam
@@ -31,3 +31,7 @@ The library is closely integrated with Hardcaml and can be easily attached
 to simulations.
 "
 conflicts: ["hardcaml-waveterm"] 
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/hardcaml_waveterm-v0.13.0.tar.gz"
+  checksum: "md5=1ab0d447fc79c059f3fcbde6ff2dcd7d"
+}
diff --git a/packages/hardcaml_waveterm/hardcaml_waveterm.v0.13.0/url b/packages/hardcaml_waveterm/hardcaml_waveterm.v0.13.0/url
deleted file mode 100644
index 03b23a61b5e..00000000000
--- a/packages/hardcaml_waveterm/hardcaml_waveterm.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/hardcaml_waveterm-v0.13.0.tar.gz"
-checksum: "1ab0d447fc79c059f3fcbde6ff2dcd7d"
diff --git a/packages/incr_dom/incr_dom.v0.13.0/opam b/packages/incr_dom/incr_dom.v0.13.0/opam
index e55a7a9836a..91e00dac8fb 100644
--- a/packages/incr_dom/incr_dom.v0.13.0/opam
+++ b/packages/incr_dom/incr_dom.v0.13.0/opam
@@ -45,3 +45,7 @@ style.
 If you want a more concrete sense of how this works, look in the
 examples directory.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_dom-v0.13.0.tar.gz"
+  checksum: "md5=2abd35e4214340ea3a55d8687cf148f9"
+}
diff --git a/packages/incr_dom/incr_dom.v0.13.0/url b/packages/incr_dom/incr_dom.v0.13.0/url
deleted file mode 100644
index 8b114a8f7cc..00000000000
--- a/packages/incr_dom/incr_dom.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_dom-v0.13.0.tar.gz"
-checksum: "2abd35e4214340ea3a55d8687cf148f9"
diff --git a/packages/incr_dom_keyboard/incr_dom_keyboard.v0.13.0/opam b/packages/incr_dom_keyboard/incr_dom_keyboard.v0.13.0/opam
index 74c174bd40b..e51cf9431f9 100644
--- a/packages/incr_dom_keyboard/incr_dom_keyboard.v0.13.0/opam
+++ b/packages/incr_dom_keyboard/incr_dom_keyboard.v0.13.0/opam
@@ -22,3 +22,7 @@ synopsis: "A library for Incr_dom keybinding and keyboard shortcut helpers"
 description: "
 This library contains code for easily creating complex application keybindings and generating help-text for those keybindings.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_dom_keyboard-v0.13.0.tar.gz"
+  checksum: "md5=087318e402d1132e4e1dc85a39052b27"
+}
diff --git a/packages/incr_dom_keyboard/incr_dom_keyboard.v0.13.0/url b/packages/incr_dom_keyboard/incr_dom_keyboard.v0.13.0/url
deleted file mode 100644
index d09ca38072d..00000000000
--- a/packages/incr_dom_keyboard/incr_dom_keyboard.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_dom_keyboard-v0.13.0.tar.gz"
-checksum: "087318e402d1132e4e1dc85a39052b27"
diff --git a/packages/incr_dom_partial_render/incr_dom_partial_render.v0.13.0/opam b/packages/incr_dom_partial_render/incr_dom_partial_render.v0.13.0/opam
index cf1cdfdfd4e..e428eeb2bb3 100644
--- a/packages/incr_dom_partial_render/incr_dom_partial_render.v0.13.0/opam
+++ b/packages/incr_dom_partial_render/incr_dom_partial_render.v0.13.0/opam
@@ -23,3 +23,7 @@ synopsis: "A library for simplifying rendering of large amounts of data"
 description: "
 This library provides tools for rendering of tabular data efficiently, in particular supporting _partial rendering_, i.e. only rendering a subset of the widgets that are logically in the view, depending on what is expected to be visible to the end user.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_dom_partial_render-v0.13.0.tar.gz"
+  checksum: "md5=62f8f390ba623b60b759c454ea70a295"
+}
diff --git a/packages/incr_dom_partial_render/incr_dom_partial_render.v0.13.0/url b/packages/incr_dom_partial_render/incr_dom_partial_render.v0.13.0/url
deleted file mode 100644
index 1b088c74cfa..00000000000
--- a/packages/incr_dom_partial_render/incr_dom_partial_render.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_dom_partial_render-v0.13.0.tar.gz"
-checksum: "62f8f390ba623b60b759c454ea70a295"
diff --git a/packages/incr_dom_widgets/incr_dom_widgets.v0.13.0/opam b/packages/incr_dom_widgets/incr_dom_widgets.v0.13.0/opam
index 4599fe56f35..b6cfd6bf8e6 100644
--- a/packages/incr_dom_widgets/incr_dom_widgets.v0.13.0/opam
+++ b/packages/incr_dom_widgets/incr_dom_widgets.v0.13.0/opam
@@ -28,3 +28,7 @@ synopsis: "Utilities for Incr_dom"
 description: "
 A collection of utilities and widgets for Incr_dom applications. Note that this library is in the process of being reorganized, and much of its present functionality will be moved out to other libraries.  Longer term, we expect this to contain easy to use wrappers of simple elements like buttons and text entry boxes.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_dom_widgets-v0.13.0.tar.gz"
+  checksum: "md5=d525eb636fe6db5f356d0c37cb5249d0"
+}
diff --git a/packages/incr_dom_widgets/incr_dom_widgets.v0.13.0/url b/packages/incr_dom_widgets/incr_dom_widgets.v0.13.0/url
deleted file mode 100644
index 58bc436abe5..00000000000
--- a/packages/incr_dom_widgets/incr_dom_widgets.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_dom_widgets-v0.13.0.tar.gz"
-checksum: "d525eb636fe6db5f356d0c37cb5249d0"
diff --git a/packages/incr_map/incr_map.v0.13.0/opam b/packages/incr_map/incr_map.v0.13.0/opam
index 3f5ee68ef1d..1c8e8205012 100644
--- a/packages/incr_map/incr_map.v0.13.0/opam
+++ b/packages/incr_map/incr_map.v0.13.0/opam
@@ -23,3 +23,7 @@ like data structures.  This leverages new functionality in Incremental
 along with the ability to efficiently diff map data structures using
 =Map.symmetric_diff=.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_map-v0.13.0.tar.gz"
+  checksum: "md5=59ed1c75aaed8921758865e036f43092"
+}
diff --git a/packages/incr_map/incr_map.v0.13.0/url b/packages/incr_map/incr_map.v0.13.0/url
deleted file mode 100644
index c17a15cb2d8..00000000000
--- a/packages/incr_map/incr_map.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_map-v0.13.0.tar.gz"
-checksum: "59ed1c75aaed8921758865e036f43092"
diff --git a/packages/incr_select/incr_select.v0.13.0/opam b/packages/incr_select/incr_select.v0.13.0/opam
index 79c7d121acd..f4fe90c5636 100644
--- a/packages/incr_select/incr_select.v0.13.0/opam
+++ b/packages/incr_select/incr_select.v0.13.0/opam
@@ -25,3 +25,7 @@ default value. The outputs are updated in time proportional to the
 number of outputs that are changed, independent of the number of
 outputs that exist.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_select-v0.13.0.tar.gz"
+  checksum: "md5=faea227ece39fd048ffd53cc2439d91a"
+}
diff --git a/packages/incr_select/incr_select.v0.13.0/url b/packages/incr_select/incr_select.v0.13.0/url
deleted file mode 100644
index 39e8bff454c..00000000000
--- a/packages/incr_select/incr_select.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incr_select-v0.13.0.tar.gz"
-checksum: "faea227ece39fd048ffd53cc2439d91a"
diff --git a/packages/incremental/incremental.v0.13.0/opam b/packages/incremental/incremental.v0.13.0/opam
index 8997c56ece6..59fc604b059 100644
--- a/packages/incremental/incremental.v0.13.0/opam
+++ b/packages/incremental/incremental.v0.13.0/opam
@@ -22,3 +22,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incremental-v0.13.0.tar.gz"
+  checksum: "md5=f2dfbc01ac1a5ddfd1e2d09523d49779"
+}
diff --git a/packages/incremental/incremental.v0.13.0/url b/packages/incremental/incremental.v0.13.0/url
deleted file mode 100644
index a1404f592b8..00000000000
--- a/packages/incremental/incremental.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/incremental-v0.13.0.tar.gz"
-checksum: "f2dfbc01ac1a5ddfd1e2d09523d49779"
diff --git a/packages/jane-street-headers/jane-street-headers.v0.13.0/opam b/packages/jane-street-headers/jane-street-headers.v0.13.0/opam
index 76fcb337c6f..9badc7ab73b 100644
--- a/packages/jane-street-headers/jane-street-headers.v0.13.0/opam
+++ b/packages/jane-street-headers/jane-street-headers.v0.13.0/opam
@@ -17,3 +17,7 @@ synopsis: "Jane Street C header files"
 description: "
 C header files shared between the various Jane Street packages
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/jane-street-headers-v0.13.0.tar.gz"
+  checksum: "md5=f06e3c111c79cdf061068b50cb61c5a4"
+}
diff --git a/packages/jane-street-headers/jane-street-headers.v0.13.0/url b/packages/jane-street-headers/jane-street-headers.v0.13.0/url
deleted file mode 100644
index e3ccd8940f1..00000000000
--- a/packages/jane-street-headers/jane-street-headers.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/jane-street-headers-v0.13.0.tar.gz"
-checksum: "f06e3c111c79cdf061068b50cb61c5a4"
diff --git a/packages/jst-config/jst-config.v0.13.0/opam b/packages/jst-config/jst-config.v0.13.0/opam
index 50f0cef1aa2..8aa71bc29ed 100644
--- a/packages/jst-config/jst-config.v0.13.0/opam
+++ b/packages/jst-config/jst-config.v0.13.0/opam
@@ -25,3 +25,7 @@ This package has an unstable interface; it is intended only to share configurati
 different packages from Jane Street. Future updates may not be backward-compatible, and we
 do not recommend using this package directly.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/jst-config-v0.13.0.tar.gz"
+  checksum: "md5=26446584781a61603014b70ad248b668"
+}
diff --git a/packages/jst-config/jst-config.v0.13.0/url b/packages/jst-config/jst-config.v0.13.0/url
deleted file mode 100644
index 6652efb9960..00000000000
--- a/packages/jst-config/jst-config.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/jst-config-v0.13.0.tar.gz"
-checksum: "26446584781a61603014b70ad248b668"
diff --git a/packages/line-up-words/line-up-words.v0.13.0/opam b/packages/line-up-words/line-up-words.v0.13.0/opam
index 2b67c387033..596fe60138d 100644
--- a/packages/line-up-words/line-up-words.v0.13.0/opam
+++ b/packages/line-up-words/line-up-words.v0.13.0/opam
@@ -25,3 +25,7 @@ in a sequence of lines in an intelligent way.
 
 It comes as a binary and an emacs mode.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/line-up-words-v0.13.0.tar.gz"
+  checksum: "md5=42147da05a17ddfd18beed51a2207fe7"
+}
diff --git a/packages/line-up-words/line-up-words.v0.13.0/url b/packages/line-up-words/line-up-words.v0.13.0/url
deleted file mode 100644
index 060b50158ee..00000000000
--- a/packages/line-up-words/line-up-words.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/line-up-words-v0.13.0.tar.gz"
-checksum: "42147da05a17ddfd18beed51a2207fe7"
diff --git a/packages/mlt_parser/mlt_parser.v0.13.0/opam b/packages/mlt_parser/mlt_parser.v0.13.0/opam
index a2bd84a542f..001869ceeb4 100644
--- a/packages/mlt_parser/mlt_parser.v0.13.0/opam
+++ b/packages/mlt_parser/mlt_parser.v0.13.0/opam
@@ -23,3 +23,7 @@ Mlt_parser contains functions for parsing .mlt files (which contain OCaml toplev
 sessions) both to power toplevel expect tests and to support a tool that converts
 .mlt files into .org files, for literate-style documentation.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/mlt_parser-v0.13.0.tar.gz"
+  checksum: "md5=7a2359aa78fd88ce9c3f85873558d962"
+}
diff --git a/packages/mlt_parser/mlt_parser.v0.13.0/url b/packages/mlt_parser/mlt_parser.v0.13.0/url
deleted file mode 100644
index 28063ebeedb..00000000000
--- a/packages/mlt_parser/mlt_parser.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/mlt_parser-v0.13.0.tar.gz"
-checksum: "7a2359aa78fd88ce9c3f85873558d962"
diff --git a/packages/netsnmp/netsnmp.v0.13.0/opam b/packages/netsnmp/netsnmp.v0.13.0/opam
index 25eddea3688..8de7ea038e6 100644
--- a/packages/netsnmp/netsnmp.v0.13.0/opam
+++ b/packages/netsnmp/netsnmp.v0.13.0/opam
@@ -23,3 +23,7 @@ description: "
 Provides a wrapper around the Net-SNMP client libraries including
 MIB handling and SNMP requests
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/netsnmp-v0.13.0.tar.gz"
+  checksum: "md5=26abf4e283a814020c36a099d9387b4b"
+}
diff --git a/packages/netsnmp/netsnmp.v0.13.0/url b/packages/netsnmp/netsnmp.v0.13.0/url
deleted file mode 100644
index 2ff1974a704..00000000000
--- a/packages/netsnmp/netsnmp.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/netsnmp-v0.13.0.tar.gz"
-checksum: "26abf4e283a814020c36a099d9387b4b"
diff --git a/packages/notty_async/notty_async.v0.13.0/opam b/packages/notty_async/notty_async.v0.13.0/opam
index a3d6782bcbc..d9f194e2bd9 100644
--- a/packages/notty_async/notty_async.v0.13.0/opam
+++ b/packages/notty_async/notty_async.v0.13.0/opam
@@ -22,3 +22,7 @@ Notty is a library for writing graphical terminal applications, and Notty_async
 is an Async driver, which makes it easy to build terminal applications using
 Async for managing concurrency.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/notty_async-v0.13.0.tar.gz"
+  checksum: "md5=11d2fa85f872f8a714a1e426b462e852"
+}
diff --git a/packages/notty_async/notty_async.v0.13.0/url b/packages/notty_async/notty_async.v0.13.0/url
deleted file mode 100644
index 493451f26ad..00000000000
--- a/packages/notty_async/notty_async.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/notty_async-v0.13.0.tar.gz"
-checksum: "11d2fa85f872f8a714a1e426b462e852"
diff --git a/packages/ocaml_plugin/ocaml_plugin.v0.13.0/opam b/packages/ocaml_plugin/ocaml_plugin.v0.13.0/opam
index 088119904b4..44d3039331d 100644
--- a/packages/ocaml_plugin/ocaml_plugin.v0.13.0/opam
+++ b/packages/ocaml_plugin/ocaml_plugin.v0.13.0/opam
@@ -22,3 +22,7 @@ depends: [
 synopsis: "Automatically build and dynlink OCaml source files"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ocaml_plugin-v0.13.0.tar.gz"
+  checksum: "md5=c2c1af79d8aedd4bf4e5709d1acf8b63"
+}
diff --git a/packages/ocaml_plugin/ocaml_plugin.v0.13.0/url b/packages/ocaml_plugin/ocaml_plugin.v0.13.0/url
deleted file mode 100644
index 832fb46da7a..00000000000
--- a/packages/ocaml_plugin/ocaml_plugin.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ocaml_plugin-v0.13.0.tar.gz"
-checksum: "c2c1af79d8aedd4bf4e5709d1acf8b63"
diff --git a/packages/pam/pam.v0.13.0/opam b/packages/pam/pam.v0.13.0/opam
index 80a3eea28f1..b2023a6964a 100644
--- a/packages/pam/pam.v0.13.0/opam
+++ b/packages/pam/pam.v0.13.0/opam
@@ -22,3 +22,7 @@ This provides OCaml bindings for the Linux-PAM (Pluggable Authentication
 Modules for Linux) library. It allows OCaml programs to delegate
 authentication tasks to the Linux-PAM framework.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/pam-v0.13.0.tar.gz"
+  checksum: "md5=37dc7b8cc6b7b63fc00f96f750a79b21"
+}
diff --git a/packages/pam/pam.v0.13.0/url b/packages/pam/pam.v0.13.0/url
deleted file mode 100644
index 7d1e59a7870..00000000000
--- a/packages/pam/pam.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/pam-v0.13.0.tar.gz"
-checksum: "37dc7b8cc6b7b63fc00f96f750a79b21"
diff --git a/packages/parsexp/parsexp.v0.13.0/opam b/packages/parsexp/parsexp.v0.13.0/opam
index ca1a0311040..323c08926f4 100644
--- a/packages/parsexp/parsexp.v0.13.0/opam
+++ b/packages/parsexp/parsexp.v0.13.0/opam
@@ -37,3 +37,7 @@ This library is portable and doesn't provide IO functions. To read
 s-expressions from files or other external sources, you should use
 parsexp_io.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/parsexp-v0.13.0.tar.gz"
+  checksum: "md5=08d2f6eca6a1eda735bf030d2581da43"
+}
diff --git a/packages/parsexp/parsexp.v0.13.0/url b/packages/parsexp/parsexp.v0.13.0/url
deleted file mode 100644
index b8dad233b97..00000000000
--- a/packages/parsexp/parsexp.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/parsexp-v0.13.0.tar.gz"
-checksum: "08d2f6eca6a1eda735bf030d2581da43"
diff --git a/packages/parsexp_io/parsexp_io.v0.13.0/opam b/packages/parsexp_io/parsexp_io.v0.13.0/opam
index 9997a5086ce..4a96020ec5c 100644
--- a/packages/parsexp_io/parsexp_io.v0.13.0/opam
+++ b/packages/parsexp_io/parsexp_io.v0.13.0/opam
@@ -21,3 +21,7 @@ synopsis: "S-expression parsing library (IO functions)"
 description: "
 Parsexp_io provides functions for loading s-expressions from files.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/parsexp_io-v0.13.0.tar.gz"
+  checksum: "md5=fd503fbf5525770fa52f740fd97ee740"
+}
diff --git a/packages/parsexp_io/parsexp_io.v0.13.0/url b/packages/parsexp_io/parsexp_io.v0.13.0/url
deleted file mode 100644
index 939bbe03675..00000000000
--- a/packages/parsexp_io/parsexp_io.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/parsexp_io-v0.13.0.tar.gz"
-checksum: "fd503fbf5525770fa52f740fd97ee740"
diff --git a/packages/patdiff/patdiff.v0.13.0/opam b/packages/patdiff/patdiff.v0.13.0/opam
index 2f0d5265919..3a4cebb91de 100644
--- a/packages/patdiff/patdiff.v0.13.0/opam
+++ b/packages/patdiff/patdiff.v0.13.0/opam
@@ -22,3 +22,7 @@ depends: [
 synopsis: "File Diff using the Patience Diff algorithm"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/patdiff-v0.13.0.tar.gz"
+  checksum: "md5=d19bf464dc5133c5b10ca8a1a0aca49e"
+}
diff --git a/packages/patdiff/patdiff.v0.13.0/url b/packages/patdiff/patdiff.v0.13.0/url
deleted file mode 100644
index 5e57c724020..00000000000
--- a/packages/patdiff/patdiff.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/patdiff-v0.13.0.tar.gz"
-checksum: "d19bf464dc5133c5b10ca8a1a0aca49e"
diff --git a/packages/patience_diff/patience_diff.v0.13.0/opam b/packages/patience_diff/patience_diff.v0.13.0/opam
index df74171a8ab..c1a0399357f 100644
--- a/packages/patience_diff/patience_diff.v0.13.0/opam
+++ b/packages/patience_diff/patience_diff.v0.13.0/opam
@@ -19,3 +19,7 @@ depends: [
 synopsis: "Diff library using Bram Cohen's patience diff algorithm"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/patience_diff-v0.13.0.tar.gz"
+  checksum: "md5=ea2e2db8a09d12e267e61d670034b9c0"
+}
diff --git a/packages/patience_diff/patience_diff.v0.13.0/url b/packages/patience_diff/patience_diff.v0.13.0/url
deleted file mode 100644
index 8ff6313a340..00000000000
--- a/packages/patience_diff/patience_diff.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/patience_diff-v0.13.0.tar.gz"
-checksum: "ea2e2db8a09d12e267e61d670034b9c0"
diff --git a/packages/posixat/posixat.v0.13.0/opam b/packages/posixat/posixat.v0.13.0/opam
index b248fc3f8a5..25e271b7394 100644
--- a/packages/posixat/posixat.v0.13.0/opam
+++ b/packages/posixat/posixat.v0.13.0/opam
@@ -25,3 +25,7 @@ The posix *at functions takes the current working directory as a file
 descriptor. For instance this allows to reliably maintain several
 working directories inside the same process.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/posixat-v0.13.0.tar.gz"
+  checksum: "md5=25c9bc258eff7ab358538f2e9565c594"
+}
diff --git a/packages/posixat/posixat.v0.13.0/url b/packages/posixat/posixat.v0.13.0/url
deleted file mode 100644
index 7abc5982b74..00000000000
--- a/packages/posixat/posixat.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/posixat-v0.13.0.tar.gz"
-checksum: "25c9bc258eff7ab358538f2e9565c594"
diff --git a/packages/postgres_async/postgres_async.v0.13.0/opam b/packages/postgres_async/postgres_async.v0.13.0/opam
index dd637b9652a..f68251cf34f 100644
--- a/packages/postgres_async/postgres_async.v0.13.0/opam
+++ b/packages/postgres_async/postgres_async.v0.13.0/opam
@@ -24,3 +24,7 @@ regular queries (including support for 'parameters': \"SELECT * WHERE a = $1\")
 and COPY IN mode. The interface presented is minimal to keep the library simple
 for now, though in the future a layer on top may add convenience functions.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/postgres_async-v0.13.0.tar.gz"
+  checksum: "md5=d8b77d39f0b3a40c46cbb258fa060934"
+}
diff --git a/packages/postgres_async/postgres_async.v0.13.0/url b/packages/postgres_async/postgres_async.v0.13.0/url
deleted file mode 100644
index e412e773e5f..00000000000
--- a/packages/postgres_async/postgres_async.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/postgres_async-v0.13.0.tar.gz"
-checksum: "d8b77d39f0b3a40c46cbb258fa060934"
diff --git a/packages/ppx_assert/ppx_assert.v0.13.0/opam b/packages/ppx_assert/ppx_assert.v0.13.0/opam
index edbb91921bc..9b5b632f917 100644
--- a/packages/ppx_assert/ppx_assert.v0.13.0/opam
+++ b/packages/ppx_assert/ppx_assert.v0.13.0/opam
@@ -23,3 +23,7 @@ synopsis: "Assert-like extension nodes that raise useful errors on failure"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_assert-v0.13.0.tar.gz"
+  checksum: "md5=89339d4982ce298156b15cf596580532"
+}
diff --git a/packages/ppx_assert/ppx_assert.v0.13.0/url b/packages/ppx_assert/ppx_assert.v0.13.0/url
deleted file mode 100644
index 01d59c7ceec..00000000000
--- a/packages/ppx_assert/ppx_assert.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_assert-v0.13.0.tar.gz"
-checksum: "89339d4982ce298156b15cf596580532"
diff --git a/packages/ppx_base/ppx_base.v0.13.0/opam b/packages/ppx_base/ppx_base.v0.13.0/opam
index 4564333393c..c86f27f52eb 100644
--- a/packages/ppx_base/ppx_base.v0.13.0/opam
+++ b/packages/ppx_base/ppx_base.v0.13.0/opam
@@ -27,3 +27,7 @@ ppx_base is the set of ppx rewriters used for Base.
 Note that Base doesn't need ppx to build, it is only used as a
 verification tool.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_base-v0.13.0.tar.gz"
+  checksum: "md5=38bcff2588008df20a39e8c74aaad0de"
+}
diff --git a/packages/ppx_base/ppx_base.v0.13.0/url b/packages/ppx_base/ppx_base.v0.13.0/url
deleted file mode 100644
index 6a9ce4d30c5..00000000000
--- a/packages/ppx_base/ppx_base.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_base-v0.13.0.tar.gz"
-checksum: "38bcff2588008df20a39e8c74aaad0de"
diff --git a/packages/ppx_bench/ppx_bench.v0.13.0/opam b/packages/ppx_bench/ppx_bench.v0.13.0/opam
index a10ba0ff05e..b73d0a9be28 100644
--- a/packages/ppx_bench/ppx_bench.v0.13.0/opam
+++ b/packages/ppx_bench/ppx_bench.v0.13.0/opam
@@ -19,3 +19,7 @@ synopsis: "Syntax extension for writing in-line benchmarks in ocaml code"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_bench-v0.13.0.tar.gz"
+  checksum: "md5=d800ee5e0b2a12401ba40e16865eabae"
+}
diff --git a/packages/ppx_bench/ppx_bench.v0.13.0/url b/packages/ppx_bench/ppx_bench.v0.13.0/url
deleted file mode 100644
index 2d0c51ef739..00000000000
--- a/packages/ppx_bench/ppx_bench.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_bench-v0.13.0.tar.gz"
-checksum: "d800ee5e0b2a12401ba40e16865eabae"
diff --git a/packages/ppx_bin_prot/ppx_bin_prot.v0.13.0/opam b/packages/ppx_bin_prot/ppx_bin_prot.v0.13.0/opam
index 65ee8665673..905ac059f14 100644
--- a/packages/ppx_bin_prot/ppx_bin_prot.v0.13.0/opam
+++ b/packages/ppx_bin_prot/ppx_bin_prot.v0.13.0/opam
@@ -21,3 +21,7 @@ synopsis: "Generation of bin_prot readers and writers from types"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_bin_prot-v0.13.0.tar.gz"
+  checksum: "md5=41129b337cacc3276aebcaf0de5437dd"
+}
diff --git a/packages/ppx_bin_prot/ppx_bin_prot.v0.13.0/url b/packages/ppx_bin_prot/ppx_bin_prot.v0.13.0/url
deleted file mode 100644
index b5a32c1343a..00000000000
--- a/packages/ppx_bin_prot/ppx_bin_prot.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_bin_prot-v0.13.0.tar.gz"
-checksum: "41129b337cacc3276aebcaf0de5437dd"
diff --git a/packages/ppx_cold/ppx_cold.v0.13.0/opam b/packages/ppx_cold/ppx_cold.v0.13.0/opam
index c9c23e87fb6..711f2109642 100644
--- a/packages/ppx_cold/ppx_cold.v0.13.0/opam
+++ b/packages/ppx_cold/ppx_cold.v0.13.0/opam
@@ -19,3 +19,7 @@ synopsis: "Expands [@cold] into [@inline never][@specialise never][@local never]
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_cold-v0.13.0.tar.gz"
+  checksum: "md5=f1ce056533573027f3579e2cac336cd6"
+}
diff --git a/packages/ppx_cold/ppx_cold.v0.13.0/url b/packages/ppx_cold/ppx_cold.v0.13.0/url
deleted file mode 100644
index 795bf18ad15..00000000000
--- a/packages/ppx_cold/ppx_cold.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_cold-v0.13.0.tar.gz"
-checksum: "f1ce056533573027f3579e2cac336cd6"
diff --git a/packages/ppx_compare/ppx_compare.v0.13.0/opam b/packages/ppx_compare/ppx_compare.v0.13.0/opam
index f060597aff1..6efa5e381d5 100644
--- a/packages/ppx_compare/ppx_compare.v0.13.0/opam
+++ b/packages/ppx_compare/ppx_compare.v0.13.0/opam
@@ -19,3 +19,7 @@ synopsis: "Generation of comparison functions from types"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_compare-v0.13.0.tar.gz"
+  checksum: "md5=17fffade1de8cfe58b768a4b28ba1d3f"
+}
diff --git a/packages/ppx_compare/ppx_compare.v0.13.0/url b/packages/ppx_compare/ppx_compare.v0.13.0/url
deleted file mode 100644
index b402d66bd66..00000000000
--- a/packages/ppx_compare/ppx_compare.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_compare-v0.13.0.tar.gz"
-checksum: "17fffade1de8cfe58b768a4b28ba1d3f"
diff --git a/packages/ppx_conv_func/ppx_conv_func.v0.13.0/opam b/packages/ppx_conv_func/ppx_conv_func.v0.13.0/opam
index 11932da8149..fe0ee7e0319 100644
--- a/packages/ppx_conv_func/ppx_conv_func.v0.13.0/opam
+++ b/packages/ppx_conv_func/ppx_conv_func.v0.13.0/opam
@@ -19,3 +19,7 @@ synopsis: "Deprecated"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_conv_func-v0.13.0.tar.gz"
+  checksum: "md5=9f4fb13856f4bfb3024bd82be1ffcd2e"
+}
diff --git a/packages/ppx_conv_func/ppx_conv_func.v0.13.0/url b/packages/ppx_conv_func/ppx_conv_func.v0.13.0/url
deleted file mode 100644
index cc0ee8ff3da..00000000000
--- a/packages/ppx_conv_func/ppx_conv_func.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_conv_func-v0.13.0.tar.gz"
-checksum: "9f4fb13856f4bfb3024bd82be1ffcd2e"
diff --git a/packages/ppx_csv_conv/ppx_csv_conv.v0.13.0/opam b/packages/ppx_csv_conv/ppx_csv_conv.v0.13.0/opam
index e4c015dff14..cb565cc6c42 100644
--- a/packages/ppx_csv_conv/ppx_csv_conv.v0.13.0/opam
+++ b/packages/ppx_csv_conv/ppx_csv_conv.v0.13.0/opam
@@ -22,3 +22,7 @@ synopsis: "Generate functions to read/write records in csv format"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_csv_conv-v0.13.0.tar.gz"
+  checksum: "md5=acef1e2c5c8175e820338f1d568961f6"
+}
diff --git a/packages/ppx_csv_conv/ppx_csv_conv.v0.13.0/url b/packages/ppx_csv_conv/ppx_csv_conv.v0.13.0/url
deleted file mode 100644
index 94cc8d6495f..00000000000
--- a/packages/ppx_csv_conv/ppx_csv_conv.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_csv_conv-v0.13.0.tar.gz"
-checksum: "acef1e2c5c8175e820338f1d568961f6"
diff --git a/packages/ppx_custom_printf/ppx_custom_printf.v0.13.0/opam b/packages/ppx_custom_printf/ppx_custom_printf.v0.13.0/opam
index 69bbb247cfc..1d315002cf1 100644
--- a/packages/ppx_custom_printf/ppx_custom_printf.v0.13.0/opam
+++ b/packages/ppx_custom_printf/ppx_custom_printf.v0.13.0/opam
@@ -20,3 +20,7 @@ synopsis: "Printf-style format-strings for user-defined string conversion"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_custom_printf-v0.13.0.tar.gz"
+  checksum: "md5=2ee27bbce00aaf0778ced96dd3eaacf9"
+}
diff --git a/packages/ppx_custom_printf/ppx_custom_printf.v0.13.0/url b/packages/ppx_custom_printf/ppx_custom_printf.v0.13.0/url
deleted file mode 100644
index 458ee2ea075..00000000000
--- a/packages/ppx_custom_printf/ppx_custom_printf.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_custom_printf-v0.13.0.tar.gz"
-checksum: "2ee27bbce00aaf0778ced96dd3eaacf9"
diff --git a/packages/ppx_deriving_hardcaml/ppx_deriving_hardcaml.v0.13.0/opam b/packages/ppx_deriving_hardcaml/ppx_deriving_hardcaml.v0.13.0/opam
index 8db817f70cb..fa902dbdd74 100644
--- a/packages/ppx_deriving_hardcaml/ppx_deriving_hardcaml.v0.13.0/opam
+++ b/packages/ppx_deriving_hardcaml/ppx_deriving_hardcaml.v0.13.0/opam
@@ -26,3 +26,7 @@ can then be accessed through the OCaml record.  This allows easier management
 of bundles of ports when working with the Simulator, Netlist generation or
 hierarchical designs.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_deriving_hardcaml-v0.13.0.tar.gz"
+  checksum: "md5=9f768eb9641de290a224dfef660970d1"
+}
diff --git a/packages/ppx_deriving_hardcaml/ppx_deriving_hardcaml.v0.13.0/url b/packages/ppx_deriving_hardcaml/ppx_deriving_hardcaml.v0.13.0/url
deleted file mode 100644
index 0ba1a8ca389..00000000000
--- a/packages/ppx_deriving_hardcaml/ppx_deriving_hardcaml.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_deriving_hardcaml-v0.13.0.tar.gz"
-checksum: "9f768eb9641de290a224dfef660970d1"
diff --git a/packages/ppx_enumerate/ppx_enumerate.v0.13.0/opam b/packages/ppx_enumerate/ppx_enumerate.v0.13.0/opam
index 5fcc45d5e4e..54f7e4b05bc 100644
--- a/packages/ppx_enumerate/ppx_enumerate.v0.13.0/opam
+++ b/packages/ppx_enumerate/ppx_enumerate.v0.13.0/opam
@@ -19,3 +19,7 @@ synopsis: "Generate a list containing all values of a finite type"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_enumerate-v0.13.0.tar.gz"
+  checksum: "md5=71182e8f76cd091daefc0fd3fb51506f"
+}
diff --git a/packages/ppx_enumerate/ppx_enumerate.v0.13.0/url b/packages/ppx_enumerate/ppx_enumerate.v0.13.0/url
deleted file mode 100644
index 76d65f2a607..00000000000
--- a/packages/ppx_enumerate/ppx_enumerate.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_enumerate-v0.13.0.tar.gz"
-checksum: "71182e8f76cd091daefc0fd3fb51506f"
diff --git a/packages/ppx_expect/ppx_expect.v0.13.0/opam b/packages/ppx_expect/ppx_expect.v0.13.0/opam
index 9ba5ade82e4..9ae9851dbbd 100644
--- a/packages/ppx_expect/ppx_expect.v0.13.0/opam
+++ b/packages/ppx_expect/ppx_expect.v0.13.0/opam
@@ -29,3 +29,7 @@ synopsis: "Cram like framework for OCaml"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_expect-v0.13.0.tar.gz"
+  checksum: "md5=e9d928f6aed89da85a511ea3d8d57f58"
+}
diff --git a/packages/ppx_expect/ppx_expect.v0.13.0/url b/packages/ppx_expect/ppx_expect.v0.13.0/url
deleted file mode 100644
index 5a82d37f255..00000000000
--- a/packages/ppx_expect/ppx_expect.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_expect-v0.13.0.tar.gz"
-checksum: "e9d928f6aed89da85a511ea3d8d57f58"
diff --git a/packages/ppx_fail/ppx_fail.v0.13.0/opam b/packages/ppx_fail/ppx_fail.v0.13.0/opam
index 3b85ca51d21..111abed6894 100644
--- a/packages/ppx_fail/ppx_fail.v0.13.0/opam
+++ b/packages/ppx_fail/ppx_fail.v0.13.0/opam
@@ -20,3 +20,7 @@ synopsis: "Add location to calls to failwiths"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_fail-v0.13.0.tar.gz"
+  checksum: "md5=f1672279f65862a6806fc7ad5aff755d"
+}
diff --git a/packages/ppx_fail/ppx_fail.v0.13.0/url b/packages/ppx_fail/ppx_fail.v0.13.0/url
deleted file mode 100644
index a8728b9b301..00000000000
--- a/packages/ppx_fail/ppx_fail.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_fail-v0.13.0.tar.gz"
-checksum: "f1672279f65862a6806fc7ad5aff755d"
diff --git a/packages/ppx_fields_conv/ppx_fields_conv.v0.13.0/opam b/packages/ppx_fields_conv/ppx_fields_conv.v0.13.0/opam
index 096b0542f95..717e3015c14 100644
--- a/packages/ppx_fields_conv/ppx_fields_conv.v0.13.0/opam
+++ b/packages/ppx_fields_conv/ppx_fields_conv.v0.13.0/opam
@@ -20,3 +20,7 @@ synopsis: "Generation of accessor and iteration functions for ocaml records"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_fields_conv-v0.13.0.tar.gz"
+  checksum: "md5=02c84db8ce53d6da9316bacae27d8d15"
+}
diff --git a/packages/ppx_fields_conv/ppx_fields_conv.v0.13.0/url b/packages/ppx_fields_conv/ppx_fields_conv.v0.13.0/url
deleted file mode 100644
index 09d5660905c..00000000000
--- a/packages/ppx_fields_conv/ppx_fields_conv.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_fields_conv-v0.13.0.tar.gz"
-checksum: "02c84db8ce53d6da9316bacae27d8d15"
diff --git a/packages/ppx_hash/ppx_hash.v0.13.0/opam b/packages/ppx_hash/ppx_hash.v0.13.0/opam
index fae49c35640..cf568a51fd4 100644
--- a/packages/ppx_hash/ppx_hash.v0.13.0/opam
+++ b/packages/ppx_hash/ppx_hash.v0.13.0/opam
@@ -21,3 +21,7 @@ synopsis: "A ppx rewriter that generates hash functions from type expressions an
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_hash-v0.13.0.tar.gz"
+  checksum: "md5=9ed5d8987bbb4f886a398ba75e8dc340"
+}
diff --git a/packages/ppx_hash/ppx_hash.v0.13.0/url b/packages/ppx_hash/ppx_hash.v0.13.0/url
deleted file mode 100644
index ed52e01b1af..00000000000
--- a/packages/ppx_hash/ppx_hash.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_hash-v0.13.0.tar.gz"
-checksum: "9ed5d8987bbb4f886a398ba75e8dc340"
diff --git a/packages/ppx_here/ppx_here.v0.13.0/opam b/packages/ppx_here/ppx_here.v0.13.0/opam
index dc227939308..44ed63984ec 100644
--- a/packages/ppx_here/ppx_here.v0.13.0/opam
+++ b/packages/ppx_here/ppx_here.v0.13.0/opam
@@ -19,3 +19,7 @@ synopsis: "Expands [%here] into its location"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_here-v0.13.0.tar.gz"
+  checksum: "md5=f11895dc064fcf56bb323423041469ed"
+}
diff --git a/packages/ppx_here/ppx_here.v0.13.0/url b/packages/ppx_here/ppx_here.v0.13.0/url
deleted file mode 100644
index fa4f6061126..00000000000
--- a/packages/ppx_here/ppx_here.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_here-v0.13.0.tar.gz"
-checksum: "f11895dc064fcf56bb323423041469ed"
diff --git a/packages/ppx_inline_test/ppx_inline_test.v0.13.0/opam b/packages/ppx_inline_test/ppx_inline_test.v0.13.0/opam
index cb1d1998e2f..c1b2a63d774 100644
--- a/packages/ppx_inline_test/ppx_inline_test.v0.13.0/opam
+++ b/packages/ppx_inline_test/ppx_inline_test.v0.13.0/opam
@@ -19,3 +19,7 @@ synopsis: "Syntax extension for writing in-line tests in ocaml code"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_inline_test-v0.13.0.tar.gz"
+  checksum: "md5=43d35d26fe496061736809e04c2df7a5"
+}
diff --git a/packages/ppx_inline_test/ppx_inline_test.v0.13.0/url b/packages/ppx_inline_test/ppx_inline_test.v0.13.0/url
deleted file mode 100644
index ca9dec108f8..00000000000
--- a/packages/ppx_inline_test/ppx_inline_test.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_inline_test-v0.13.0.tar.gz"
-checksum: "43d35d26fe496061736809e04c2df7a5"
diff --git a/packages/ppx_jane/ppx_jane.v0.13.0/opam b/packages/ppx_jane/ppx_jane.v0.13.0/opam
index 9151ce9d48f..a01fe6da416 100644
--- a/packages/ppx_jane/ppx_jane.v0.13.0/opam
+++ b/packages/ppx_jane/ppx_jane.v0.13.0/opam
@@ -40,3 +40,7 @@ description: "
 This package installs a ppx-jane executable, which is a ppx driver
 including all standard Jane Street ppx rewriters.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_jane-v0.13.0.tar.gz"
+  checksum: "md5=a0bfd0e6e98455622e1993be6ba48c70"
+}
diff --git a/packages/ppx_jane/ppx_jane.v0.13.0/url b/packages/ppx_jane/ppx_jane.v0.13.0/url
deleted file mode 100644
index 66e082f902d..00000000000
--- a/packages/ppx_jane/ppx_jane.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_jane-v0.13.0.tar.gz"
-checksum: "a0bfd0e6e98455622e1993be6ba48c70"
diff --git a/packages/ppx_js_style/ppx_js_style.v0.13.0/opam b/packages/ppx_js_style/ppx_js_style.v0.13.0/opam
index dd7217b0345..4782aeb9df5 100644
--- a/packages/ppx_js_style/ppx_js_style.v0.13.0/opam
+++ b/packages/ppx_js_style/ppx_js_style.v0.13.0/opam
@@ -23,3 +23,7 @@ Part of the Jane Street's PPX rewriters collection.
 This packages is a no-op ppx rewriter. It is used as a 'lint' tool to
 enforce some coding conventions across all Jane Street packages.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_js_style-v0.13.0.tar.gz"
+  checksum: "md5=812426d228741010fb275e0689b14c64"
+}
diff --git a/packages/ppx_js_style/ppx_js_style.v0.13.0/url b/packages/ppx_js_style/ppx_js_style.v0.13.0/url
deleted file mode 100644
index 85e515b741c..00000000000
--- a/packages/ppx_js_style/ppx_js_style.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_js_style-v0.13.0.tar.gz"
-checksum: "812426d228741010fb275e0689b14c64"
diff --git a/packages/ppx_let/ppx_let.v0.13.0/opam b/packages/ppx_let/ppx_let.v0.13.0/opam
index 8f4acd3e307..34433ac88f0 100644
--- a/packages/ppx_let/ppx_let.v0.13.0/opam
+++ b/packages/ppx_let/ppx_let.v0.13.0/opam
@@ -19,3 +19,7 @@ synopsis: "Monadic let-bindings"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_let-v0.13.0.tar.gz"
+  checksum: "md5=8b5fab936fffa4b02f786ef18ab0c877"
+}
diff --git a/packages/ppx_let/ppx_let.v0.13.0/url b/packages/ppx_let/ppx_let.v0.13.0/url
deleted file mode 100644
index 1790951b7e9..00000000000
--- a/packages/ppx_let/ppx_let.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_let-v0.13.0.tar.gz"
-checksum: "8b5fab936fffa4b02f786ef18ab0c877"
diff --git a/packages/ppx_module_timer/ppx_module_timer.v0.13.0/opam b/packages/ppx_module_timer/ppx_module_timer.v0.13.0/opam
index e6aa8485dc6..16f842c11d4 100644
--- a/packages/ppx_module_timer/ppx_module_timer.v0.13.0/opam
+++ b/packages/ppx_module_timer/ppx_module_timer.v0.13.0/opam
@@ -22,3 +22,7 @@ synopsis: "Ppx rewriter that records top-level module startup times"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_module_timer-v0.13.0.tar.gz"
+  checksum: "md5=b0765d8807f2f7402e5e0c822037ce02"
+}
diff --git a/packages/ppx_module_timer/ppx_module_timer.v0.13.0/url b/packages/ppx_module_timer/ppx_module_timer.v0.13.0/url
deleted file mode 100644
index 561f05785a2..00000000000
--- a/packages/ppx_module_timer/ppx_module_timer.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_module_timer-v0.13.0.tar.gz"
-checksum: "b0765d8807f2f7402e5e0c822037ce02"
diff --git a/packages/ppx_optcomp/ppx_optcomp.v0.13.0/opam b/packages/ppx_optcomp/ppx_optcomp.v0.13.0/opam
index 09ecbc61f5d..ea1967743c3 100644
--- a/packages/ppx_optcomp/ppx_optcomp.v0.13.0/opam
+++ b/packages/ppx_optcomp/ppx_optcomp.v0.13.0/opam
@@ -20,3 +20,7 @@ synopsis: "Optional compilation for OCaml"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_optcomp-v0.13.0.tar.gz"
+  checksum: "md5=662b62fbc8349f2894073ecdd4d34d63"
+}
diff --git a/packages/ppx_optcomp/ppx_optcomp.v0.13.0/url b/packages/ppx_optcomp/ppx_optcomp.v0.13.0/url
deleted file mode 100644
index 2c18717acbe..00000000000
--- a/packages/ppx_optcomp/ppx_optcomp.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_optcomp-v0.13.0.tar.gz"
-checksum: "662b62fbc8349f2894073ecdd4d34d63"
diff --git a/packages/ppx_optional/ppx_optional.v0.13.0/opam b/packages/ppx_optional/ppx_optional.v0.13.0/opam
index fce67e898b6..48d8f733e61 100644
--- a/packages/ppx_optional/ppx_optional.v0.13.0/opam
+++ b/packages/ppx_optional/ppx_optional.v0.13.0/opam
@@ -20,3 +20,7 @@ description: "
 A ppx rewriter that rewrites simple match statements with an if then
 else expression.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_optional-v0.13.0.tar.gz"
+  checksum: "md5=e9b763741e21f66579fb3ac0230ee772"
+}
diff --git a/packages/ppx_optional/ppx_optional.v0.13.0/url b/packages/ppx_optional/ppx_optional.v0.13.0/url
deleted file mode 100644
index e2edea5d603..00000000000
--- a/packages/ppx_optional/ppx_optional.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_optional-v0.13.0.tar.gz"
-checksum: "e9b763741e21f66579fb3ac0230ee772"
diff --git a/packages/ppx_pattern_bind/ppx_pattern_bind.v0.13.0/opam b/packages/ppx_pattern_bind/ppx_pattern_bind.v0.13.0/opam
index d9c9e7d2707..3c8b58df730 100644
--- a/packages/ppx_pattern_bind/ppx_pattern_bind.v0.13.0/opam
+++ b/packages/ppx_pattern_bind/ppx_pattern_bind.v0.13.0/opam
@@ -19,3 +19,7 @@ A ppx rewriter that is intended for use with Incremental. It makes it
 easier to write incremental computations using pattern-matching in a
 way that causes incremental nodes to fire as little as possible.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_pattern_bind-v0.13.0.tar.gz"
+  checksum: "md5=fe45e8f153daea058bbfa8bfa0bb864d"
+}
diff --git a/packages/ppx_pattern_bind/ppx_pattern_bind.v0.13.0/url b/packages/ppx_pattern_bind/ppx_pattern_bind.v0.13.0/url
deleted file mode 100644
index 3955359ad22..00000000000
--- a/packages/ppx_pattern_bind/ppx_pattern_bind.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_pattern_bind-v0.13.0.tar.gz"
-checksum: "fe45e8f153daea058bbfa8bfa0bb864d"
diff --git a/packages/ppx_pipebang/ppx_pipebang.v0.13.0/opam b/packages/ppx_pipebang/ppx_pipebang.v0.13.0/opam
index 83e30b7c6e9..57813b538a8 100644
--- a/packages/ppx_pipebang/ppx_pipebang.v0.13.0/opam
+++ b/packages/ppx_pipebang/ppx_pipebang.v0.13.0/opam
@@ -18,3 +18,7 @@ synopsis: "A ppx rewriter that inlines reverse application operators `|>` and `|
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_pipebang-v0.13.0.tar.gz"
+  checksum: "md5=59660363b73f80e880dfd9fbecaef04b"
+}
diff --git a/packages/ppx_pipebang/ppx_pipebang.v0.13.0/url b/packages/ppx_pipebang/ppx_pipebang.v0.13.0/url
deleted file mode 100644
index b6f8711d125..00000000000
--- a/packages/ppx_pipebang/ppx_pipebang.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_pipebang-v0.13.0.tar.gz"
-checksum: "59660363b73f80e880dfd9fbecaef04b"
diff --git a/packages/ppx_python/ppx_python.v0.13.0/opam b/packages/ppx_python/ppx_python.v0.13.0/opam
index 58e70edf1bb..0b282ec0abf 100644
--- a/packages/ppx_python/ppx_python.v0.13.0/opam
+++ b/packages/ppx_python/ppx_python.v0.13.0/opam
@@ -21,3 +21,7 @@ synopsis: "[@@deriving] plugin to generate Python conversion functions"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_python-v0.13.0.tar.gz"
+  checksum: "md5=1693819df7db90947379382ea1f5545a"
+}
diff --git a/packages/ppx_python/ppx_python.v0.13.0/url b/packages/ppx_python/ppx_python.v0.13.0/url
deleted file mode 100644
index 212aba8320a..00000000000
--- a/packages/ppx_python/ppx_python.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_python-v0.13.0.tar.gz"
-checksum: "1693819df7db90947379382ea1f5545a"
diff --git a/packages/ppx_sexp_conv/ppx_sexp_conv.v0.13.0/opam b/packages/ppx_sexp_conv/ppx_sexp_conv.v0.13.0/opam
index 58aeb7cf3c8..d40a58424a2 100644
--- a/packages/ppx_sexp_conv/ppx_sexp_conv.v0.13.0/opam
+++ b/packages/ppx_sexp_conv/ppx_sexp_conv.v0.13.0/opam
@@ -20,3 +20,7 @@ synopsis: "[@@deriving] plugin to generate S-expression conversion functions"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_sexp_conv-v0.13.0.tar.gz"
+  checksum: "md5=acb33a38721f4a16f71add6afaa315da"
+}
diff --git a/packages/ppx_sexp_conv/ppx_sexp_conv.v0.13.0/url b/packages/ppx_sexp_conv/ppx_sexp_conv.v0.13.0/url
deleted file mode 100644
index 695ecdf1c3d..00000000000
--- a/packages/ppx_sexp_conv/ppx_sexp_conv.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_sexp_conv-v0.13.0.tar.gz"
-checksum: "acb33a38721f4a16f71add6afaa315da"
diff --git a/packages/ppx_sexp_message/ppx_sexp_message.v0.13.0/opam b/packages/ppx_sexp_message/ppx_sexp_message.v0.13.0/opam
index 01ca51c229f..bf2db0ef28e 100644
--- a/packages/ppx_sexp_message/ppx_sexp_message.v0.13.0/opam
+++ b/packages/ppx_sexp_message/ppx_sexp_message.v0.13.0/opam
@@ -21,3 +21,7 @@ synopsis: "A ppx rewriter for easy construction of s-expressions"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_sexp_message-v0.13.0.tar.gz"
+  checksum: "md5=3bff70327d98e67e85749ef50bcc5d96"
+}
diff --git a/packages/ppx_sexp_message/ppx_sexp_message.v0.13.0/url b/packages/ppx_sexp_message/ppx_sexp_message.v0.13.0/url
deleted file mode 100644
index b16cda72b01..00000000000
--- a/packages/ppx_sexp_message/ppx_sexp_message.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_sexp_message-v0.13.0.tar.gz"
-checksum: "3bff70327d98e67e85749ef50bcc5d96"
diff --git a/packages/ppx_sexp_value/ppx_sexp_value.v0.13.0/opam b/packages/ppx_sexp_value/ppx_sexp_value.v0.13.0/opam
index 405e5a74350..fb0e4e863ce 100644
--- a/packages/ppx_sexp_value/ppx_sexp_value.v0.13.0/opam
+++ b/packages/ppx_sexp_value/ppx_sexp_value.v0.13.0/opam
@@ -21,3 +21,7 @@ synopsis: "A ppx rewriter that simplifies building s-expressions from ocaml valu
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_sexp_value-v0.13.0.tar.gz"
+  checksum: "md5=81073d573bcf045b0000a7ea264bd25f"
+}
diff --git a/packages/ppx_sexp_value/ppx_sexp_value.v0.13.0/url b/packages/ppx_sexp_value/ppx_sexp_value.v0.13.0/url
deleted file mode 100644
index 21a15e8b7f0..00000000000
--- a/packages/ppx_sexp_value/ppx_sexp_value.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_sexp_value-v0.13.0.tar.gz"
-checksum: "81073d573bcf045b0000a7ea264bd25f"
diff --git a/packages/ppx_stable/ppx_stable.v0.13.0/opam b/packages/ppx_stable/ppx_stable.v0.13.0/opam
index 331d00628ee..042adb9175d 100644
--- a/packages/ppx_stable/ppx_stable.v0.13.0/opam
+++ b/packages/ppx_stable/ppx_stable.v0.13.0/opam
@@ -20,3 +20,7 @@ description: "
 A ppx extension for easier implementation of conversion functions between almost
 identical types.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_stable-v0.13.0.tar.gz"
+  checksum: "md5=e014ba0629db3bc5d4e3022f9d3615ea"
+}
diff --git a/packages/ppx_stable/ppx_stable.v0.13.0/url b/packages/ppx_stable/ppx_stable.v0.13.0/url
deleted file mode 100644
index 92280ae8a5c..00000000000
--- a/packages/ppx_stable/ppx_stable.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_stable-v0.13.0.tar.gz"
-checksum: "e014ba0629db3bc5d4e3022f9d3615ea"
diff --git a/packages/ppx_typerep_conv/ppx_typerep_conv.v0.13.0/opam b/packages/ppx_typerep_conv/ppx_typerep_conv.v0.13.0/opam
index 20bb364c022..4ff6a54d80f 100644
--- a/packages/ppx_typerep_conv/ppx_typerep_conv.v0.13.0/opam
+++ b/packages/ppx_typerep_conv/ppx_typerep_conv.v0.13.0/opam
@@ -20,3 +20,7 @@ synopsis: "Generation of runtime types from type declarations"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_typerep_conv-v0.13.0.tar.gz"
+  checksum: "md5=8940a4c65887cc7f46bdaa83e3e1105a"
+}
diff --git a/packages/ppx_typerep_conv/ppx_typerep_conv.v0.13.0/url b/packages/ppx_typerep_conv/ppx_typerep_conv.v0.13.0/url
deleted file mode 100644
index 8147dc7bd10..00000000000
--- a/packages/ppx_typerep_conv/ppx_typerep_conv.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_typerep_conv-v0.13.0.tar.gz"
-checksum: "8940a4c65887cc7f46bdaa83e3e1105a"
diff --git a/packages/ppx_variants_conv/ppx_variants_conv.v0.13.0/opam b/packages/ppx_variants_conv/ppx_variants_conv.v0.13.0/opam
index 394f924e569..a6337019041 100644
--- a/packages/ppx_variants_conv/ppx_variants_conv.v0.13.0/opam
+++ b/packages/ppx_variants_conv/ppx_variants_conv.v0.13.0/opam
@@ -20,3 +20,7 @@ synopsis: "Generation of accessor and iteration functions for ocaml variant type
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_variants_conv-v0.13.0.tar.gz"
+  checksum: "md5=75e957c4fd6efbf2f4a6de08f2729729"
+}
diff --git a/packages/ppx_variants_conv/ppx_variants_conv.v0.13.0/url b/packages/ppx_variants_conv/ppx_variants_conv.v0.13.0/url
deleted file mode 100644
index 32ec9194e1a..00000000000
--- a/packages/ppx_variants_conv/ppx_variants_conv.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_variants_conv-v0.13.0.tar.gz"
-checksum: "75e957c4fd6efbf2f4a6de08f2729729"
diff --git a/packages/ppx_xml_conv/ppx_xml_conv.v0.13.0/opam b/packages/ppx_xml_conv/ppx_xml_conv.v0.13.0/opam
index 338b97a499c..251a71f2906 100644
--- a/packages/ppx_xml_conv/ppx_xml_conv.v0.13.0/opam
+++ b/packages/ppx_xml_conv/ppx_xml_conv.v0.13.0/opam
@@ -22,3 +22,7 @@ synopsis: "Generate XML conversion functions from records"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_xml_conv-v0.13.0.tar.gz"
+  checksum: "md5=3b6e04381605f16a1120168354301071"
+}
diff --git a/packages/ppx_xml_conv/ppx_xml_conv.v0.13.0/url b/packages/ppx_xml_conv/ppx_xml_conv.v0.13.0/url
deleted file mode 100644
index 89fb9380e5a..00000000000
--- a/packages/ppx_xml_conv/ppx_xml_conv.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_xml_conv-v0.13.0.tar.gz"
-checksum: "3b6e04381605f16a1120168354301071"
diff --git a/packages/ppx_yojson_conv/ppx_yojson_conv.v0.13.0/opam b/packages/ppx_yojson_conv/ppx_yojson_conv.v0.13.0/opam
index e88aec09bc4..31197fb20fd 100644
--- a/packages/ppx_yojson_conv/ppx_yojson_conv.v0.13.0/opam
+++ b/packages/ppx_yojson_conv/ppx_yojson_conv.v0.13.0/opam
@@ -21,3 +21,7 @@ synopsis: "[@@deriving] plugin to generate Yojson conversion functions"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_yojson_conv-v0.13.0.tar.gz"
+  checksum: "md5=86785af654d2f26b7cf7a6be375543c4"
+}
diff --git a/packages/ppx_yojson_conv/ppx_yojson_conv.v0.13.0/url b/packages/ppx_yojson_conv/ppx_yojson_conv.v0.13.0/url
deleted file mode 100644
index 6f948d04696..00000000000
--- a/packages/ppx_yojson_conv/ppx_yojson_conv.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_yojson_conv-v0.13.0.tar.gz"
-checksum: "86785af654d2f26b7cf7a6be375543c4"
diff --git a/packages/ppx_yojson_conv_lib/ppx_yojson_conv_lib.v0.13.0/opam b/packages/ppx_yojson_conv_lib/ppx_yojson_conv_lib.v0.13.0/opam
index 0c01ac0f031..9d7e73eb4ee 100644
--- a/packages/ppx_yojson_conv_lib/ppx_yojson_conv_lib.v0.13.0/opam
+++ b/packages/ppx_yojson_conv_lib/ppx_yojson_conv_lib.v0.13.0/opam
@@ -18,3 +18,7 @@ synopsis: "Runtime lib for ppx_yojson_conv"
 description: "
 Part of the Jane Street's PPX rewriters collection.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_yojson_conv_lib-v0.13.0.tar.gz"
+  checksum: "md5=790fade9ecff5767dd48cd49c9bba2f3"
+}
diff --git a/packages/ppx_yojson_conv_lib/ppx_yojson_conv_lib.v0.13.0/url b/packages/ppx_yojson_conv_lib/ppx_yojson_conv_lib.v0.13.0/url
deleted file mode 100644
index 7dc41cb665c..00000000000
--- a/packages/ppx_yojson_conv_lib/ppx_yojson_conv_lib.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/ppx_yojson_conv_lib-v0.13.0.tar.gz"
-checksum: "790fade9ecff5767dd48cd49c9bba2f3"
diff --git a/packages/protocol_version_header/protocol_version_header.v0.13.0/opam b/packages/protocol_version_header/protocol_version_header.v0.13.0/opam
index b918a7a9e01..4a9a98f3167 100644
--- a/packages/protocol_version_header/protocol_version_header.v0.13.0/opam
+++ b/packages/protocol_version_header/protocol_version_header.v0.13.0/opam
@@ -22,3 +22,7 @@ version themselves. The more protocols that add themselves to
 [Known_protocol], the nicer error messages we will get when connecting
 to a service while using the wrong protocol.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/protocol_version_header-v0.13.0.tar.gz"
+  checksum: "md5=44cd282a3161ca738ec0baf9f411a27e"
+}
diff --git a/packages/protocol_version_header/protocol_version_header.v0.13.0/url b/packages/protocol_version_header/protocol_version_header.v0.13.0/url
deleted file mode 100644
index 256fd3d986a..00000000000
--- a/packages/protocol_version_header/protocol_version_header.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/protocol_version_header-v0.13.0.tar.gz"
-checksum: "44cd282a3161ca738ec0baf9f411a27e"
diff --git a/packages/pythonlib/pythonlib.v0.13.0/opam b/packages/pythonlib/pythonlib.v0.13.0/opam
index 647eeb32809..a2cbebbd36d 100644
--- a/packages/pythonlib/pythonlib.v0.13.0/opam
+++ b/packages/pythonlib/pythonlib.v0.13.0/opam
@@ -23,3 +23,7 @@ synopsis: "A library to help writing wrappers around ocaml code for python"
 description: "
 This library helps exposing ocaml functions to python. The python runtime interaction is handled by pyml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/pythonlib-v0.13.0.tar.gz"
+  checksum: "md5=be1f1a4a527b2ce28c8c1308183848cd"
+}
diff --git a/packages/pythonlib/pythonlib.v0.13.0/url b/packages/pythonlib/pythonlib.v0.13.0/url
deleted file mode 100644
index 02bc1eee5a0..00000000000
--- a/packages/pythonlib/pythonlib.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/pythonlib-v0.13.0.tar.gz"
-checksum: "be1f1a4a527b2ce28c8c1308183848cd"
diff --git a/packages/re2/re2.v0.13.0/opam b/packages/re2/re2.v0.13.0/opam
index 0b3193440d6..b8df63dbd1f 100644
--- a/packages/re2/re2.v0.13.0/opam
+++ b/packages/re2/re2.v0.13.0/opam
@@ -22,3 +22,7 @@ depexts: [
  [ ["fedora"] ["gcc-c++"] ]
  [ ["oraclelinux"] ["gcc-c++"] ]
 ]
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/re2-v0.13.0.tar.gz"
+  checksum: "md5=8f9bfddd8e58efd050262683a8469b9b"
+}
diff --git a/packages/re2/re2.v0.13.0/url b/packages/re2/re2.v0.13.0/url
deleted file mode 100644
index 3e14fed0896..00000000000
--- a/packages/re2/re2.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/re2-v0.13.0.tar.gz"
-checksum: "8f9bfddd8e58efd050262683a8469b9b"
diff --git a/packages/record_builder/record_builder.v0.13.0/opam b/packages/record_builder/record_builder.v0.13.0/opam
index cb33ac1630d..68f95e142f9 100644
--- a/packages/record_builder/record_builder.v0.13.0/opam
+++ b/packages/record_builder/record_builder.v0.13.0/opam
@@ -23,3 +23,7 @@ derived =Fields.make_creator= function for a given record type. The wrapper
 automatically handles all of the mapping and combining of applicative terms
 needed to build the record from a single applicative term for each field.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/record_builder-v0.13.0.tar.gz"
+  checksum: "md5=0c90f0dd509081e35f154fcf49764c2d"
+}
diff --git a/packages/record_builder/record_builder.v0.13.0/url b/packages/record_builder/record_builder.v0.13.0/url
deleted file mode 100644
index 4082e18e5cf..00000000000
--- a/packages/record_builder/record_builder.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/record_builder-v0.13.0.tar.gz"
-checksum: "0c90f0dd509081e35f154fcf49764c2d"
diff --git a/packages/resource_cache/resource_cache.v0.13.0/opam b/packages/resource_cache/resource_cache.v0.13.0/opam
index cec2acbf124..7d9ffb1955f 100644
--- a/packages/resource_cache/resource_cache.v0.13.0/opam
+++ b/packages/resource_cache/resource_cache.v0.13.0/opam
@@ -23,3 +23,7 @@ This library offers a functor to create a resource cache over some
 abstract [Resource] type. The cache enables resource reuse while
 obeying various limits.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/resource_cache-v0.13.0.tar.gz"
+  checksum: "md5=65041292edcb8a0c3577b454f76acbaa"
+}
diff --git a/packages/resource_cache/resource_cache.v0.13.0/url b/packages/resource_cache/resource_cache.v0.13.0/url
deleted file mode 100644
index 6881a3d6292..00000000000
--- a/packages/resource_cache/resource_cache.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/resource_cache-v0.13.0.tar.gz"
-checksum: "65041292edcb8a0c3577b454f76acbaa"
diff --git a/packages/rpc_parallel/rpc_parallel.v0.13.0/opam b/packages/rpc_parallel/rpc_parallel.v0.13.0/opam
index f58e3cad3b9..d69c5965e24 100644
--- a/packages/rpc_parallel/rpc_parallel.v0.13.0/opam
+++ b/packages/rpc_parallel/rpc_parallel.v0.13.0/opam
@@ -25,3 +25,7 @@ spawn workers as separate processes, and communicate with them using
 Async Rpc.
 
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/rpc_parallel-v0.13.0.tar.gz"
+  checksum: "md5=1a2e33449294291a3290b5a9b0142554"
+}
diff --git a/packages/rpc_parallel/rpc_parallel.v0.13.0/url b/packages/rpc_parallel/rpc_parallel.v0.13.0/url
deleted file mode 100644
index c7c6a72cdbd..00000000000
--- a/packages/rpc_parallel/rpc_parallel.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/rpc_parallel-v0.13.0.tar.gz"
-checksum: "1a2e33449294291a3290b5a9b0142554"
diff --git a/packages/sequencer_table/sequencer_table.v0.13.0/opam b/packages/sequencer_table/sequencer_table.v0.13.0/opam
index 79fdd9fe902..295dff09fa1 100644
--- a/packages/sequencer_table/sequencer_table.v0.13.0/opam
+++ b/packages/sequencer_table/sequencer_table.v0.13.0/opam
@@ -19,3 +19,7 @@ synopsis: "A table of [Async.Sequencer]'s, indexed by key"
 description: "
 A single-module library for a data structure.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sequencer_table-v0.13.0.tar.gz"
+  checksum: "md5=13643e8caf081550058f1840597796c3"
+}
diff --git a/packages/sequencer_table/sequencer_table.v0.13.0/url b/packages/sequencer_table/sequencer_table.v0.13.0/url
deleted file mode 100644
index 6f5a8a4d66a..00000000000
--- a/packages/sequencer_table/sequencer_table.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sequencer_table-v0.13.0.tar.gz"
-checksum: "13643e8caf081550058f1840597796c3"
diff --git a/packages/sexp/sexp.v0.13.0/opam b/packages/sexp/sexp.v0.13.0/opam
index 8b23248120b..ed434445b8b 100644
--- a/packages/sexp/sexp.v0.13.0/opam
+++ b/packages/sexp/sexp.v0.13.0/opam
@@ -30,3 +30,7 @@ A suite of tools for working with s-expressions from the command line.
 It contains subcommands for pretty printing, querying, and modifying
 sexps, as well as some conversions to and from other formats.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexp-v0.13.0.tar.gz"
+  checksum: "md5=d8883201993f2249272ad53640e2a406"
+}
diff --git a/packages/sexp/sexp.v0.13.0/url b/packages/sexp/sexp.v0.13.0/url
deleted file mode 100644
index 2b27fd9c942..00000000000
--- a/packages/sexp/sexp.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexp-v0.13.0.tar.gz"
-checksum: "d8883201993f2249272ad53640e2a406"
diff --git a/packages/sexp_diff_kernel/sexp_diff_kernel.v0.13.0/opam b/packages/sexp_diff_kernel/sexp_diff_kernel.v0.13.0/opam
index d8c6c4295fa..7523023e671 100644
--- a/packages/sexp_diff_kernel/sexp_diff_kernel.v0.13.0/opam
+++ b/packages/sexp_diff_kernel/sexp_diff_kernel.v0.13.0/opam
@@ -20,3 +20,7 @@ description: "
 The code behind the [diff] subcommand of the Jane Street's [sexp]
 command line tool.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexp_diff_kernel-v0.13.0.tar.gz"
+  checksum: "md5=bea4eb37c594dbe3b408378debea37cb"
+}
diff --git a/packages/sexp_diff_kernel/sexp_diff_kernel.v0.13.0/url b/packages/sexp_diff_kernel/sexp_diff_kernel.v0.13.0/url
deleted file mode 100644
index bdd80866590..00000000000
--- a/packages/sexp_diff_kernel/sexp_diff_kernel.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexp_diff_kernel-v0.13.0.tar.gz"
-checksum: "bea4eb37c594dbe3b408378debea37cb"
diff --git a/packages/sexp_macro/sexp_macro.v0.13.0/opam b/packages/sexp_macro/sexp_macro.v0.13.0/opam
index 355114842dd..074d53d5bbc 100644
--- a/packages/sexp_macro/sexp_macro.v0.13.0/opam
+++ b/packages/sexp_macro/sexp_macro.v0.13.0/opam
@@ -21,3 +21,7 @@ description: "
 Sexp macros allow the user to define and use constants and simple functions in sexp files,
 include one sexp file in another.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexp_macro-v0.13.0.tar.gz"
+  checksum: "md5=63d2b5ae80ff5898f6e277ea8d6f824e"
+}
diff --git a/packages/sexp_macro/sexp_macro.v0.13.0/url b/packages/sexp_macro/sexp_macro.v0.13.0/url
deleted file mode 100644
index 4248b0f7d4f..00000000000
--- a/packages/sexp_macro/sexp_macro.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexp_macro-v0.13.0.tar.gz"
-checksum: "63d2b5ae80ff5898f6e277ea8d6f824e"
diff --git a/packages/sexp_pretty/sexp_pretty.v0.13.0/opam b/packages/sexp_pretty/sexp_pretty.v0.13.0/opam
index 91a47300931..e52f5de6cb3 100644
--- a/packages/sexp_pretty/sexp_pretty.v0.13.0/opam
+++ b/packages/sexp_pretty/sexp_pretty.v0.13.0/opam
@@ -22,3 +22,7 @@ description: "
 A library for pretty-printing s-expressions, using better indentation rules than
 the default pretty printer in Sexplib.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexp_pretty-v0.13.0.tar.gz"
+  checksum: "md5=02968817ee8df34f1c60bf66c1f0437c"
+}
diff --git a/packages/sexp_pretty/sexp_pretty.v0.13.0/url b/packages/sexp_pretty/sexp_pretty.v0.13.0/url
deleted file mode 100644
index f8c469c1581..00000000000
--- a/packages/sexp_pretty/sexp_pretty.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexp_pretty-v0.13.0.tar.gz"
-checksum: "02968817ee8df34f1c60bf66c1f0437c"
diff --git a/packages/sexp_select/sexp_select.v0.13.0/opam b/packages/sexp_select/sexp_select.v0.13.0/opam
index cac1fb819b5..999ed90b65f 100644
--- a/packages/sexp_select/sexp_select.v0.13.0/opam
+++ b/packages/sexp_select/sexp_select.v0.13.0/opam
@@ -20,3 +20,7 @@ description: "
 This library provides a convenient method to traverse sexp trees
 and return subtrees that match the given program.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexp_select-v0.13.0.tar.gz"
+  checksum: "md5=56a5f4ea28de3a99e59ef1271d11af02"
+}
diff --git a/packages/sexp_select/sexp_select.v0.13.0/url b/packages/sexp_select/sexp_select.v0.13.0/url
deleted file mode 100644
index 2606f1cac3a..00000000000
--- a/packages/sexp_select/sexp_select.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexp_select-v0.13.0.tar.gz"
-checksum: "56a5f4ea28de3a99e59ef1271d11af02"
diff --git a/packages/sexplib/sexplib.v0.13.0/opam b/packages/sexplib/sexplib.v0.13.0/opam
index c5378e43178..a618c82a641 100644
--- a/packages/sexplib/sexplib.v0.13.0/opam
+++ b/packages/sexplib/sexplib.v0.13.0/opam
@@ -23,3 +23,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexplib-v0.13.0.tar.gz"
+  checksum: "md5=d3dd8eb6f10e64e6766217bf6b57bc93"
+}
diff --git a/packages/sexplib/sexplib.v0.13.0/url b/packages/sexplib/sexplib.v0.13.0/url
deleted file mode 100644
index 05965a5561d..00000000000
--- a/packages/sexplib/sexplib.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexplib-v0.13.0.tar.gz"
-checksum: "d3dd8eb6f10e64e6766217bf6b57bc93"
diff --git a/packages/sexplib0/sexplib0.v0.13.0/opam b/packages/sexplib0/sexplib0.v0.13.0/opam
index 08168435e37..27626b3c346 100644
--- a/packages/sexplib0/sexplib0.v0.13.0/opam
+++ b/packages/sexplib0/sexplib0.v0.13.0/opam
@@ -20,3 +20,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexplib0-v0.13.0.tar.gz"
+  checksum: "md5=f8a715dffda5599cfae0cb4031d57abe"
+}
diff --git a/packages/sexplib0/sexplib0.v0.13.0/url b/packages/sexplib0/sexplib0.v0.13.0/url
deleted file mode 100644
index a5261daeb54..00000000000
--- a/packages/sexplib0/sexplib0.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/sexplib0-v0.13.0.tar.gz"
-checksum: "f8a715dffda5599cfae0cb4031d57abe"
diff --git a/packages/shell/shell.v0.13.0/opam b/packages/shell/shell.v0.13.0/opam
index 2b40e486ed2..832bcf27ebb 100644
--- a/packages/shell/shell.v0.13.0/opam
+++ b/packages/shell/shell.v0.13.0/opam
@@ -25,3 +25,7 @@ description: "
 This library is a relatively featureful and flexible implementation of fork&exec with related functionality, including some basic support for asynchronous I/O. This is an old and unmaintained code. New users are advised to try using [Async.Process] for certain use cases and [Shexp_process] for certain other use cases.
 "
 depexts: ["linux-headers"] {os-distribution = "alpine"}
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/shell-v0.13.0.tar.gz"
+  checksum: "md5=e4562149241675e796086e62d6fbd6ce"
+}
diff --git a/packages/shell/shell.v0.13.0/url b/packages/shell/shell.v0.13.0/url
deleted file mode 100644
index 065ac4cb0a0..00000000000
--- a/packages/shell/shell.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/shell-v0.13.0.tar.gz"
-checksum: "e4562149241675e796086e62d6fbd6ce"
diff --git a/packages/shexp/shexp.v0.13.0/opam b/packages/shexp/shexp.v0.13.0/opam
index 338824408dc..f44aa76af4e 100644
--- a/packages/shexp/shexp.v0.13.0/opam
+++ b/packages/shexp/shexp.v0.13.0/opam
@@ -23,3 +23,7 @@ Shexp is composed of two parts: a library providing a process monad
 for shell scripting in OCaml as well as a simple s-expression based
 shell interpreter. Shexp works on both Unix and Windows.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/shexp-v0.13.0.tar.gz"
+  checksum: "md5=13002fde6249703d06ff820906cd96c9"
+}
diff --git a/packages/shexp/shexp.v0.13.0/url b/packages/shexp/shexp.v0.13.0/url
deleted file mode 100644
index c8939e84def..00000000000
--- a/packages/shexp/shexp.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/shexp-v0.13.0.tar.gz"
-checksum: "13002fde6249703d06ff820906cd96c9"
diff --git a/packages/splay_tree/splay_tree.v0.13.0/opam b/packages/splay_tree/splay_tree.v0.13.0/opam
index 3426c659d55..47950600830 100644
--- a/packages/splay_tree/splay_tree.v0.13.0/opam
+++ b/packages/splay_tree/splay_tree.v0.13.0/opam
@@ -29,3 +29,7 @@ Notably, this splay tree implementation is parameterized by a
 reduction operation which lets you specify an extra accumulator value,
 which can then be searched by efficiently.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/splay_tree-v0.13.0.tar.gz"
+  checksum: "md5=fd926dcdef1c6db78f450687c7e40cde"
+}
diff --git a/packages/splay_tree/splay_tree.v0.13.0/url b/packages/splay_tree/splay_tree.v0.13.0/url
deleted file mode 100644
index 75c728346be..00000000000
--- a/packages/splay_tree/splay_tree.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/splay_tree-v0.13.0.tar.gz"
-checksum: "fd926dcdef1c6db78f450687c7e40cde"
diff --git a/packages/splittable_random/splittable_random.v0.13.0/opam b/packages/splittable_random/splittable_random.v0.13.0/opam
index 13c53b41c5e..b6dd335595a 100644
--- a/packages/splittable_random/splittable_random.v0.13.0/opam
+++ b/packages/splittable_random/splittable_random.v0.13.0/opam
@@ -29,3 +29,7 @@ independent stream of random values.
 This library implements a splittable pseudo-random number generator that sacrifices
 cryptographic-quality randomness in favor of performance.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/splittable_random-v0.13.0.tar.gz"
+  checksum: "md5=3894b41a18a6b011c3b7e32e0d645044"
+}
diff --git a/packages/splittable_random/splittable_random.v0.13.0/url b/packages/splittable_random/splittable_random.v0.13.0/url
deleted file mode 100644
index 6a3312cf985..00000000000
--- a/packages/splittable_random/splittable_random.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/splittable_random-v0.13.0.tar.gz"
-checksum: "3894b41a18a6b011c3b7e32e0d645044"
diff --git a/packages/stdio/stdio.v0.13.0/opam b/packages/stdio/stdio.v0.13.0/opam
index 6c7ad2ad075..42d6f14d58b 100644
--- a/packages/stdio/stdio.v0.13.0/opam
+++ b/packages/stdio/stdio.v0.13.0/opam
@@ -21,3 +21,7 @@ Stdio implements simple input/output functionalities for OCaml.
 It re-exports the input/output functions of the OCaml standard
 libraries using a more consistent API.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/stdio-v0.13.0.tar.gz"
+  checksum: "md5=48ef28512ddd51ff9885649dd1fab91d"
+}
diff --git a/packages/stdio/stdio.v0.13.0/url b/packages/stdio/stdio.v0.13.0/url
deleted file mode 100644
index f8ae43fd8d9..00000000000
--- a/packages/stdio/stdio.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/stdio-v0.13.0.tar.gz"
-checksum: "48ef28512ddd51ff9885649dd1fab91d"
diff --git a/packages/string_dict/string_dict.v0.13.0/opam b/packages/string_dict/string_dict.v0.13.0/opam
index b56233ec70b..59b6926269a 100644
--- a/packages/string_dict/string_dict.v0.13.0/opam
+++ b/packages/string_dict/string_dict.v0.13.0/opam
@@ -25,3 +25,7 @@ dictionary is created.
 This uses the algorithm the OCaml compiler uses for pattern matching
 on strings.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/string_dict-v0.13.0.tar.gz"
+  checksum: "md5=d59386f70c238316854e2b4c7a17471f"
+}
diff --git a/packages/string_dict/string_dict.v0.13.0/url b/packages/string_dict/string_dict.v0.13.0/url
deleted file mode 100644
index c61f0d3f2b0..00000000000
--- a/packages/string_dict/string_dict.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/string_dict-v0.13.0.tar.gz"
-checksum: "d59386f70c238316854e2b4c7a17471f"
diff --git a/packages/textutils/textutils.v0.13.0/opam b/packages/textutils/textutils.v0.13.0/opam
index 13e058bcc9b..9f60ef3253a 100644
--- a/packages/textutils/textutils.v0.13.0/opam
+++ b/packages/textutils/textutils.v0.13.0/opam
@@ -18,3 +18,7 @@ depends: [
 synopsis: "Text output utilities"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/textutils-v0.13.0.tar.gz"
+  checksum: "md5=90123c1e72d94adbde4727a59e8e6a63"
+}
diff --git a/packages/textutils/textutils.v0.13.0/url b/packages/textutils/textutils.v0.13.0/url
deleted file mode 100644
index 50af7f0fa86..00000000000
--- a/packages/textutils/textutils.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/textutils-v0.13.0.tar.gz"
-checksum: "90123c1e72d94adbde4727a59e8e6a63"
diff --git a/packages/textutils_kernel/textutils_kernel.v0.13.0/opam b/packages/textutils_kernel/textutils_kernel.v0.13.0/opam
index e951a7bbaa3..9686023d46f 100644
--- a/packages/textutils_kernel/textutils_kernel.v0.13.0/opam
+++ b/packages/textutils_kernel/textutils_kernel.v0.13.0/opam
@@ -18,3 +18,7 @@ depends: [
 synopsis: "Text output utilities"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/textutils_kernel-v0.13.0.tar.gz"
+  checksum: "md5=eb5421c78ffb9a1fd9521020c00f0e95"
+}
diff --git a/packages/textutils_kernel/textutils_kernel.v0.13.0/url b/packages/textutils_kernel/textutils_kernel.v0.13.0/url
deleted file mode 100644
index e65c473362d..00000000000
--- a/packages/textutils_kernel/textutils_kernel.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/textutils_kernel-v0.13.0.tar.gz"
-checksum: "eb5421c78ffb9a1fd9521020c00f0e95"
diff --git a/packages/time_now/time_now.v0.13.0/opam b/packages/time_now/time_now.v0.13.0/opam
index 80a73e37f77..704c0271cc4 100644
--- a/packages/time_now/time_now.v0.13.0/opam
+++ b/packages/time_now/time_now.v0.13.0/opam
@@ -23,3 +23,7 @@ description: "
 Provides a single function to report the current time in nanoseconds
 since the start of the Unix epoch.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/time_now-v0.13.0.tar.gz"
+  checksum: "md5=d0b5550426f40b142bf41de5f83745e6"
+}
diff --git a/packages/time_now/time_now.v0.13.0/url b/packages/time_now/time_now.v0.13.0/url
deleted file mode 100644
index 20ceb908937..00000000000
--- a/packages/time_now/time_now.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/time_now-v0.13.0.tar.gz"
-checksum: "d0b5550426f40b142bf41de5f83745e6"
diff --git a/packages/timezone/timezone.v0.13.0/opam b/packages/timezone/timezone.v0.13.0/opam
index b7529852d67..e6f448aca28 100644
--- a/packages/timezone/timezone.v0.13.0/opam
+++ b/packages/timezone/timezone.v0.13.0/opam
@@ -20,3 +20,7 @@ description: "
 Timezone handles parsing timezone data and create [Timezone.t] that
 can later be used to manipulate time in core_kernel or core.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/timezone-v0.13.0.tar.gz"
+  checksum: "md5=ef4d2ba9efb9a4599dc432af3f876bba"
+}
diff --git a/packages/timezone/timezone.v0.13.0/url b/packages/timezone/timezone.v0.13.0/url
deleted file mode 100644
index ba188542ed3..00000000000
--- a/packages/timezone/timezone.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/timezone-v0.13.0.tar.gz"
-checksum: "ef4d2ba9efb9a4599dc432af3f876bba"
diff --git a/packages/toplevel_backend/toplevel_backend.v0.13.0/opam b/packages/toplevel_backend/toplevel_backend.v0.13.0/opam
index 7be02830dd2..801d7c32cdd 100644
--- a/packages/toplevel_backend/toplevel_backend.v0.13.0/opam
+++ b/packages/toplevel_backend/toplevel_backend.v0.13.0/opam
@@ -21,3 +21,7 @@ synopsis: "Shared backend for setting up toplevels"
 description: "
 Module for setting up dependencies (like printers and liblinks) for toplevels.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/toplevel_backend-v0.13.0.tar.gz"
+  checksum: "md5=d8c00771884f1d0ef3f057e9405de631"
+}
diff --git a/packages/toplevel_backend/toplevel_backend.v0.13.0/url b/packages/toplevel_backend/toplevel_backend.v0.13.0/url
deleted file mode 100644
index 8bdf24003b8..00000000000
--- a/packages/toplevel_backend/toplevel_backend.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/toplevel_backend-v0.13.0.tar.gz"
-checksum: "d8c00771884f1d0ef3f057e9405de631"
diff --git a/packages/toplevel_expect_test/toplevel_expect_test.v0.13.0/opam b/packages/toplevel_expect_test/toplevel_expect_test.v0.13.0/opam
index 6dff84f3b44..0406668e2b9 100644
--- a/packages/toplevel_expect_test/toplevel_expect_test.v0.13.0/opam
+++ b/packages/toplevel_expect_test/toplevel_expect_test.v0.13.0/opam
@@ -31,3 +31,7 @@ the toplevel in the same file. This provides an easy way to test
 compilations errors as well as provide a nice alternative to using
 the toplevel in a terminal.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/toplevel_expect_test-v0.13.0.tar.gz"
+  checksum: "md5=342b516c8654616c670e5b27ae69dc89"
+}
diff --git a/packages/toplevel_expect_test/toplevel_expect_test.v0.13.0/url b/packages/toplevel_expect_test/toplevel_expect_test.v0.13.0/url
deleted file mode 100644
index 1ec8aff305e..00000000000
--- a/packages/toplevel_expect_test/toplevel_expect_test.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/toplevel_expect_test-v0.13.0.tar.gz"
-checksum: "342b516c8654616c670e5b27ae69dc89"
diff --git a/packages/topological_sort/topological_sort.v0.13.0/opam b/packages/topological_sort/topological_sort.v0.13.0/opam
index 78349fd2721..6246fe8662c 100644
--- a/packages/topological_sort/topological_sort.v0.13.0/opam
+++ b/packages/topological_sort/topological_sort.v0.13.0/opam
@@ -21,3 +21,7 @@ description: "
 Topological_sort is a single-module library that implements a simple
 topological-sort algorithm.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/topological_sort-v0.13.0.tar.gz"
+  checksum: "md5=5f3510c5c65bdc751d1e9767af195116"
+}
diff --git a/packages/topological_sort/topological_sort.v0.13.0/url b/packages/topological_sort/topological_sort.v0.13.0/url
deleted file mode 100644
index 97fe2c4afcd..00000000000
--- a/packages/topological_sort/topological_sort.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/topological_sort-v0.13.0.tar.gz"
-checksum: "5f3510c5c65bdc751d1e9767af195116"
diff --git a/packages/typerep/typerep.v0.13.0/opam b/packages/typerep/typerep.v0.13.0/opam
index 40b47a8d22d..7ad0104c65c 100644
--- a/packages/typerep/typerep.v0.13.0/opam
+++ b/packages/typerep/typerep.v0.13.0/opam
@@ -17,3 +17,7 @@ depends: [
 synopsis: "Typerep is a library for runtime types"
 description: "
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/typerep-v0.13.0.tar.gz"
+  checksum: "md5=226109522c9509d2c849a33f110c2a0b"
+}
diff --git a/packages/typerep/typerep.v0.13.0/url b/packages/typerep/typerep.v0.13.0/url
deleted file mode 100644
index f8868f5602b..00000000000
--- a/packages/typerep/typerep.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/typerep-v0.13.0.tar.gz"
-checksum: "226109522c9509d2c849a33f110c2a0b"
diff --git a/packages/variantslib/variantslib.v0.13.0/opam b/packages/variantslib/variantslib.v0.13.0/opam
index 435e8981b20..b3d395e246d 100644
--- a/packages/variantslib/variantslib.v0.13.0/opam
+++ b/packages/variantslib/variantslib.v0.13.0/opam
@@ -20,3 +20,7 @@ The Core suite of libraries is an industrial strength alternative to
 OCaml's standard library that was developed by Jane Street, the
 largest industrial user of OCaml.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/variantslib-v0.13.0.tar.gz"
+  checksum: "md5=8fdcf18a0146a2004a2faa1d4b907ab3"
+}
diff --git a/packages/variantslib/variantslib.v0.13.0/url b/packages/variantslib/variantslib.v0.13.0/url
deleted file mode 100644
index f9e399e8ec8..00000000000
--- a/packages/variantslib/variantslib.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/variantslib-v0.13.0.tar.gz"
-checksum: "8fdcf18a0146a2004a2faa1d4b907ab3"
diff --git a/packages/virtual_dom/virtual_dom.v0.13.0/opam b/packages/virtual_dom/virtual_dom.v0.13.0/opam
index 7aab0b55614..7aa657b9655 100644
--- a/packages/virtual_dom/virtual_dom.v0.13.0/opam
+++ b/packages/virtual_dom/virtual_dom.v0.13.0/opam
@@ -24,3 +24,7 @@ description: "
 The library itself may be found at
 https://github.com/Matt-Esch/virtual-dom.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/virtual_dom-v0.13.0.tar.gz"
+  checksum: "md5=ef2c93a9bd968b44e09fee501f853a2d"
+}
diff --git a/packages/virtual_dom/virtual_dom.v0.13.0/url b/packages/virtual_dom/virtual_dom.v0.13.0/url
deleted file mode 100644
index 43515d0f494..00000000000
--- a/packages/virtual_dom/virtual_dom.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/virtual_dom-v0.13.0.tar.gz"
-checksum: "ef2c93a9bd968b44e09fee501f853a2d"
diff --git a/packages/zarith_stubs_js/zarith_stubs_js.v0.13.0/opam b/packages/zarith_stubs_js/zarith_stubs_js.v0.13.0/opam
index fad4f9db33e..33181a1680e 100644
--- a/packages/zarith_stubs_js/zarith_stubs_js.v0.13.0/opam
+++ b/packages/zarith_stubs_js/zarith_stubs_js.v0.13.0/opam
@@ -18,3 +18,7 @@ description: "
 This library contains no ocaml code, but instead implements
 all of the Zarith C stubs in Javascript for use in Js_of_ocaml
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/zarith_stubs_js-v0.13.0.tar.gz"
+  checksum: "md5=6c48a15eb7b0a41d9b53a1c4915a8a6b"
+}
diff --git a/packages/zarith_stubs_js/zarith_stubs_js.v0.13.0/url b/packages/zarith_stubs_js/zarith_stubs_js.v0.13.0/url
deleted file mode 100644
index 3c177570008..00000000000
--- a/packages/zarith_stubs_js/zarith_stubs_js.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/zarith_stubs_js-v0.13.0.tar.gz"
-checksum: "6c48a15eb7b0a41d9b53a1c4915a8a6b"
diff --git a/packages/zstandard/zstandard.v0.13.0/opam b/packages/zstandard/zstandard.v0.13.0/opam
index 866d71cae4a..75efd0a14bb 100644
--- a/packages/zstandard/zstandard.v0.13.0/opam
+++ b/packages/zstandard/zstandard.v0.13.0/opam
@@ -21,3 +21,7 @@ synopsis: "OCaml bindings to Zstandard"
 description: "
 Zstandard is a real-time compression algorithm which provides high compression ratios.
 "
+url {
+  src: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/zstandard-v0.13.0.tar.gz"
+  checksum: "md5=ce3b9c47beda368bf4664a447ab47a02"
+}
diff --git a/packages/zstandard/zstandard.v0.13.0/url b/packages/zstandard/zstandard.v0.13.0/url
deleted file mode 100644
index 0022e99e533..00000000000
--- a/packages/zstandard/zstandard.v0.13.0/url
+++ /dev/null
@@ -1,2 +0,0 @@
-archive: "https://ocaml.janestreet.com/ocaml-core/v0.13/files/zstandard-v0.13.0.tar.gz"
-checksum: "ce3b9c47beda368bf4664a447ab47a02"