diff --git a/nix/build-support/stacklock2nix/default.nix b/nix/build-support/stacklock2nix/default.nix
index 116ca11..6c1e3f5 100644
--- a/nix/build-support/stacklock2nix/default.nix
+++ b/nix/build-support/stacklock2nix/default.nix
@@ -185,12 +185,14 @@ let
   # file.
   resolverParsed = readYAML resolverRawYaml;
 
-  fetchCabalFileRevision =
-    let
-      args =
-        lib.optionalAttrs (all-cabal-hashes != null) { inherit all-cabal-hashes; };
-    in
-    callPackage ./fetchCabalFileRevision.nix args;
+  # Fetch cabal revisions from the stackage content addressable store.
+  fetchCabalFileRevision = {name, version, hash}:
+    fetchurl {
+      pname = "${name}-cabal";
+      inherit version;
+      url = "https://casa.stackage.org/${hash}";
+      sha256 = hash;
+    };
 
   # Replace the `.cabal` file in a given Haskell package with the revision
   # specified by the given hash.
diff --git a/nix/build-support/stacklock2nix/fetchCabalFileRevision.nix b/nix/build-support/stacklock2nix/fetchCabalFileRevision.nix
deleted file mode 100644
index b6a29bd..0000000
--- a/nix/build-support/stacklock2nix/fetchCabalFileRevision.nix
+++ /dev/null
@@ -1,50 +0,0 @@
-
-{ all-cabal-hashes, curl, coreutils, lib, stdenvNoCC, writeShellScript }:
-
-# Fetch the revision of a `.cabal` file for a given Haskell package from
-# Hackage.
-
-{ # Haskell package.
-  #
-  # name :: String
-  #
-  # Example: `"lens"`
-  name
-, # Version
-  #
-  # version :: String
-  #
-  # Example: `"5.0.1"`
-  version
-, # Hash of the revised `.cabal` file from Hackage.
-  #
-  # hash :: String
-  #
-  # Example: "63ed57e4d54c583ae2873d6892ef690942d90030864d0b772413a1458e98159f"
-  hash
-}:
-
-stdenvNoCC.mkDerivation {
-
-  name = "${name}-${version}-cabal-file";
-
-  outputHashAlgo = "sha256";
-  outputHash = hash;
-  outputHashMode = "flat";
-
-  nativeBuildInputs = [
-    coreutils # TODO: needed for seq.  remove this dependency.
-    curl
-  ];
-
-  nixpkgsVersion = lib.trivial.release;
-
-  builder = ./fetchCabalFileRevisionBuilder.sh;
-
-  # Arguments used in builder script.
-
-  haskPkgName = name;
-  haskPkgVer = version;
-  haskPkgHash = hash;
-  all_cabal_hashes = all-cabal-hashes;
-}
diff --git a/nix/build-support/stacklock2nix/fetchCabalFileRevisionBuilder.sh b/nix/build-support/stacklock2nix/fetchCabalFileRevisionBuilder.sh
deleted file mode 100644
index 9062d81..0000000
--- a/nix/build-support/stacklock2nix/fetchCabalFileRevisionBuilder.sh
+++ /dev/null
@@ -1,136 +0,0 @@
-
-# This script gets the following arguments:
-#
-# $haskPkgName:  The name of the haskell package to look for.
-#
-# $haskPkgVer:  The version of the haskell package to look for.
-#
-# $haskPkgHash:  The hash of the specific revision of the .cabal file to look for.
-#
-# $all_cabal_hashes:  A path to the all-cabal-hashes derivation.
-
-source $stdenv/setup
-
-set -euo pipefail
-
-# Try to extract the .cabal file for the given revision
-#
-# Arguments:
-#   (none)
-#
-# Returns:
-#   0:         If the given .cabal revision was found in the tarball.
-#   non-zero:  If the given .cabal revision was not found in the tarball.
-#
-# Side effects:
-#   Creates the file "./${haskPkgName}.cabal" if the given revision was found
-#   in the tarball.
-find_cabal_file_in_all_cabal_hashes () {
-  if [ -d "${all_cabal_hashes}" ]; then
-    # all-cabal-hashes is a directory.  Directly reference the .cabal file need.
-    cp "${all_cabal_hashes}/${haskPkgName}/${haskPkgVer}/${haskPkgName}.cabal" ./
-  else
-    # all-cabal-hashes is a tarball.  Try to pull out the .cabal file we need.
-    tar --wildcards --extract --file "${all_cabal_hashes}" \
-        --gzip --strip-components=3 "*/${haskPkgName}/${haskPkgVer}/${haskPkgName}.cabal"
-  fi
-}
-
-# Test the hash of the file "./${haskPkgName}.cabal" to see if it is equal to
-# the passed-in hash.
-#
-# Arguments:
-#   (none)
-#
-# Returns:
-#   0:         If the hashes are equal.
-#   non-zero:  If the hashes are not equal
-#
-# Side effects:
-#   (none)
-test_hash () {
-  fileSha=$(sha256sum "${haskPkgName}.cabal" | cut -d' ' -f1)
-  [[ "$fileSha" == "${haskPkgHash}" ]]
-}
-
-# Copies the "./${haskPkgName}.cabal" file to "$out" and exits.
-#
-# Arguments:
-#   (none)
-#
-# Returns:
-#   (none)
-#
-# Side effects:
-#   Exits
-copy_cabal_file_to_out_and_exit () {
-  cp "${haskPkgName}.cabal" "$out"
-  exit 0
-}
-
-# TODO: check if all-cabal-hashes is a directory, and don't do this in that case
-
-
-# This will look for the given revision of the cabal file in
-# all-cabal-hashes. This will loop while incrementing the revision ID to
-# look for.
-#
-# If a .cabal file is found with the correct hash, it is used.  Otherwise,
-# this loop ends when there are no more revision IDs available for the
-# package/version.
-if find_cabal_file_in_all_cabal_hashes; then
-  # We successfully extracted the tar file, now we see if it has the
-  # correct hash.
-  if test_hash ; then
-    # The file has the correct hash
-    copy_cabal_file_to_out_and_exit
-  fi
-
-  # Remove the .cabal file because the hash doesn't match.
-  rm "${haskPkgName}.cabal"
-fi
-
-echo "Couldn't find .cabal file revision for ${haskPkgName}-${haskPkgVer} in all-cabal-hashes.  Fetching from Hackage..."
-
-curlVersion=$(curl -V | head -1 | cut -d' ' -f2)
-
-curl=(
-    curl
-    --location
-    --max-redirs 20
-    --retry 3
-    --disable-epsv
-    --cookie-jar cookies
-    --user-agent "curl/$curlVersion Nixpkgs/$nixpkgsVersion"
-    --insecure
-)
-
-# This is pretty dumb.
-#
-# The snapshot/resolver specified in a stack.yaml contains the hash of the
-# revised `.cabal` file that should be used for each package, but it
-# doesn't contain the _number_ of the revision the hash belongs to.
-# Unfortunately, Hackage only provides a way to download a `.cabal` file
-# based on a revision number (not a revised `.cabal` file given a hash).
-#
-# So the following code attempts to download each revised `.cabal` file for
-# a version of a package, one-by-one, hash it, and check whether the hash
-# matches the hash we are looking for.  If it does, we're good to go.
-#
-# In theory, this should always succeed, since the Stackage snapshots
-# will only reference `.cabal` file revisions from Hackage.  In practice,
-# I've never seen this fail to find a revision, but who knows what weird
-# things go on in the edge-cases of Hackage.
-
-for hackageRevisionId in $(seq 0 20) ; do
-  echo "$hackageRevisionId"
-  revisionUrl="https://hackage.haskell.org/package/${haskPkgName}-${haskPkgVer}/revision/${hackageRevisionId}.cabal"
-  "${curl[@]}" -L "$revisionUrl" > "${haskPkgName}.cabal"
-  if test_hash ; then
-    copy_cabal_file_to_out_and_exit
-  fi
-  rm "${haskPkgName}.cabal"
-done
-
-echo "ERROR: Could not find cabal file revision for ${haskPkgName}-${haskPkgVer} with hash ${haskPkgHash} in Hackage"
-exit 1