diff --git a/src/dune_rules/ctypes/ctypes_rules.ml b/src/dune_rules/ctypes/ctypes_rules.ml
index d27cc6d1396e..2388ea285d6a 100644
--- a/src/dune_rules/ctypes/ctypes_rules.ml
+++ b/src/dune_rules/ctypes/ctypes_rules.ml
@@ -483,8 +483,7 @@ let gen_rules ~cctx ~(buildable : Buildable.t) ~loc ~scope ~dir ~sctx =
           ~c_types_includer_module))
 ;;
 
-let ctypes_cclib_flags sctx ~expander ~(buildable : Buildable.t) =
-  let standard = Action_builder.return [] in
+let ctypes_cclib_flags ?(standard = Action_builder.return []) sctx ~expander ~(buildable : Buildable.t)  =
   match buildable.ctypes with
   | None -> standard
   | Some ctypes ->
diff --git a/src/dune_rules/ctypes/ctypes_rules.mli b/src/dune_rules/ctypes/ctypes_rules.mli
index 27c1241e1179..689d8673c50d 100644
--- a/src/dune_rules/ctypes/ctypes_rules.mli
+++ b/src/dune_rules/ctypes/ctypes_rules.mli
@@ -10,7 +10,8 @@ val gen_rules
   -> unit Memo.t
 
 val ctypes_cclib_flags
-  :  Super_context.t
+  : ?standard:(string list Action_builder.t)
+  ->  Super_context.t
   -> expander:Expander.t
   -> buildable:Dune_file.Buildable.t
   -> string list Action_builder.t
diff --git a/src/dune_rules/lib_rules.ml b/src/dune_rules/lib_rules.ml
index b362c67b72a1..96c98b2ff15b 100644
--- a/src/dune_rules/lib_rules.ml
+++ b/src/dune_rules/lib_rules.ml
@@ -331,9 +331,7 @@ let build_stubs lib ~cctx ~dir ~expander ~requires ~dir_contents ~vlib_stubs_o_f
         Cxx_flags.get_flags ~for_:Link (Context.build_context ctx)
       | _ -> Action_builder.return []
     in
-    let c_library_flags =
-      Expander.expand_and_eval_set expander lib.c_library_flags ~standard
-    in
+    let c_library_flags = Ctypes_rules.ctypes_cclib_flags sctx ~expander ~buildable:lib.buildable ~standard in
     let lib_o_files_for_all_modes = Mode.Map.Multi.for_all_modes o_files in
     let for_all_modes = List.rev_append vlib_stubs_o_files lib_o_files_for_all_modes in
     if Mode.Dict.Set.to_list modes.ocaml
diff --git a/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/dune b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/dune
new file mode 100644
index 000000000000..2ca1e427745b
--- /dev/null
+++ b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/dune
@@ -0,0 +1,4 @@
+(executable
+ (name example)
+ (modes byte)
+ (libraries examplelib))
diff --git a/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/dune-project b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/dune-project
new file mode 100644
index 000000000000..d993321861b0
--- /dev/null
+++ b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/dune-project
@@ -0,0 +1,3 @@
+(lang dune 3.10)
+
+(using ctypes 0.3)
diff --git a/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/example.ml b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/example.ml
new file mode 100644
index 000000000000..eebafeb3114f
--- /dev/null
+++ b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/example.ml
@@ -0,0 +1,2 @@
+let () =
+  Printf.printf "%d\n" (Examplelib.C.Functions.add2 2)
diff --git a/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/run.t b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/run.t
new file mode 100644
index 000000000000..a3f2ba295ba6
--- /dev/null
+++ b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/run.t
@@ -0,0 +1,24 @@
+Build an example library as a DLL and set up the environment so that it looks
+like a system/distro library that can be probed with pkg-config and dynamically
+loaded.
+
+Run the program in bytecode
+  $ LIBEX=$(realpath "$PWD/../libexample")
+
+ocamlrun + requires CAML_LD_LIBRARY_PATH such that dlopen can find
+dllexamplelib_stub.so
+
+Explictly set {DYLD,LD}_LIBRARY_PATH at runtime for this testcase, otherwise
+dlopen cannot find libexample.
+
+  $  PKG_CONFIG_PATH="$LIBEX/pkgconfig" PKG_CONFIG_ARGN="--define-prefix" DYLD_LIBRARY_PATH="$DYLD_LIBRARY_PATH:$LIBEX" LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$LIBEX" CAML_LD_LIBRARY_PATH="$CAML_LD_LIBRARY_PATH:$PWD/_build/default/stubgen" dune exec ./example.bc
+  4
+
+Utop works with ctypes pkg-config external library.
+
+  $   DYLD_LIBRARY_PATH="$DYLD_LIBRARY_PATH:$LIBEX" LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$LIBEX"  PKG_CONFIG_PATH="$LIBEX/pkgconfig" PKG_CONFIG_ARGN="--define-prefix" dune utop --display=short ./ -- example.ml
+    pkg-config stubgen/.pkg-config/libexample.cflags
+    pkg-config stubgen/.pkg-config/libexample.libs
+        ocamlc .utop/.utop.eobjs/byte/dune__exe__Utop.{cmi,cmo,cmt}
+        ocamlc .utop/utop.bc
+  4
diff --git a/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/dune b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/dune
new file mode 100644
index 000000000000..a426491271df
--- /dev/null
+++ b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/dune
@@ -0,0 +1,14 @@
+(library
+  (name examplelib)
+  (flags (:standard -w -9-27))
+  (ctypes
+    (external_library_name libexample)
+    (build_flags_resolver pkg_config)
+    (headers (include "example.h"))
+    (type_description
+      (instance Types)
+      (functor Type_description))
+    (function_description
+      (instance Functions)
+      (functor Function_description))
+    (generated_entry_point C)))
diff --git a/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/function_description.ml b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/function_description.ml
new file mode 100644
index 000000000000..05c43d79e2fa
--- /dev/null
+++ b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/function_description.ml
@@ -0,0 +1,8 @@
+open Ctypes
+
+module Types = Types_generated
+
+module Functions (F : Ctypes.FOREIGN) = struct
+  open F
+  let add2 = foreign "example_add2" (int @-> returning int)
+end
diff --git a/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/type_description.ml b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/type_description.ml
new file mode 100644
index 000000000000..41693fda9b31
--- /dev/null
+++ b/test/blackbox-tests/test-cases/ctypes/bytecode-stubs-external-lib.t/stubgen/type_description.ml
@@ -0,0 +1,3 @@
+module Types (F : Ctypes.TYPE) = struct
+
+end
diff --git a/test/blackbox-tests/test-cases/ctypes/dune b/test/blackbox-tests/test-cases/ctypes/dune
index 3d9ec9e03096..a3d6c3586aac 100644
--- a/test/blackbox-tests/test-cases/ctypes/dune
+++ b/test/blackbox-tests/test-cases/ctypes/dune
@@ -27,6 +27,7 @@
 
 (cram
  (applies_to
+  bytecode-stubs-external-lib
   lib-pkg_config
   lib-pkg_config-multiple-fd
   lib-external-name-need-mangling