diff --git a/gnu/local.mk b/gnu/local.mk
index 1f26871a13e..953b1403bc3 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1942,6 +1942,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/nvi-db4.patch				\
   %D%/packages/patches/nyacc-binary-literals.patch		\
   %D%/packages/patches/obs-modules-location.patch		\
+  %D%/packages/patches/ocaml-ctypes-test-oo.patch		\
   %D%/packages/patches/ocaml-multiple-definitions.patch		\
   %D%/packages/patches/ogre-next-add-riscv64-support.patch		\
   %D%/packages/patches/ocaml-4.07-dynamically-allocate-signal-stack.patch	\
diff --git a/gnu/packages/ocaml.scm b/gnu/packages/ocaml.scm
index 88c9241e205..16ff501bdb2 100644
--- a/gnu/packages/ocaml.scm
+++ b/gnu/packages/ocaml.scm
@@ -15,7 +15,7 @@
 ;;; Copyright © 2019 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2020 Brett Gilio <brettg@gnu.org>
 ;;; Copyright © 2020 Marius Bakke <marius@gnu.org>
-;;; Copyright © 2020, 2021 Simon Tournier <zimon.toutoune@gmail.com>
+;;; Copyright © 2020, 2021, 2025 Simon Tournier <zimon.toutoune@gmail.com>
 ;;; Copyright © 2020 divoplade <d@divoplade.fr>
 ;;; Copyright © 2020, 2021, 2022 pukkamustard <pukkamustard@posteo.net>
 ;;; Copyright © 2021 aecepoglu <aecepoglu@fastmail.fm>
@@ -5698,7 +5698,7 @@ long and size_t whose sizes depend on the host platform.")
 (define-public ocaml-ctypes
   (package
    (name "ocaml-ctypes")
-   (version "0.20.1")
+   (version "0.23.0")
    (home-page "https://github.com/ocamllabs/ocaml-ctypes")
    (source (origin
              (method git-fetch)
@@ -5708,8 +5708,9 @@ long and size_t whose sizes depend on the host platform.")
              (file-name (git-file-name name version))
              (sha256
               (base32
-               "0ilzq9qzvwv9rc08cc9wchsx636zp870i7qvqmbigaa2qb812m0z"))))
-   (build-system ocaml-build-system)
+               "16dxz2r070vlrkbqhza0c5y6izxpjn080vqmxj47i919wfqd75vx"))
+             (patches (search-patches "ocaml-ctypes-test-oo.patch"))))
+   (build-system dune-build-system)
    (arguments
     `(#:phases
       (modify-phases %standard-phases
diff --git a/gnu/packages/patches/ocaml-ctypes-test-oo.patch b/gnu/packages/patches/ocaml-ctypes-test-oo.patch
new file mode 100644
index 00000000000..7cb797d07d5
--- /dev/null
+++ b/gnu/packages/patches/ocaml-ctypes-test-oo.patch
@@ -0,0 +1,49 @@
+Backport upstream commit fe4be538e389d5caf6c0a562cd02e58fda9361cb.
+
+    Add an explicit upcast in the OO-style test.
+
+https://github.com/yallop/ocaml-ctypes/commit/fe4be538e389d5caf6c0a562cd02e58fda9361cb
+
+It allows to deal with GCC@14 stricter than the previous versions.
+
+diff --git a/tests/clib/test_functions.c b/tests/clib/test_functions.c
+index d19db2b..486b7d1 100644
+--- a/tests/clib/test_functions.c
++++ b/tests/clib/test_functions.c
+@@ -293,6 +293,11 @@ struct chorse *new_chorse(int colour)
+   h->colour = (enum colour)colour;
+   return h;
+ }
++
++struct animal *new_chorse_as_animal(int colour)
++{
++  return (struct animal *)new_chorse(colour);
++}
+ /* (End of OO-style example) */
+ 
+ int accept_pointers(float *float_p,
+diff --git a/tests/clib/test_functions.h b/tests/clib/test_functions.h
+index 5022e98..579f622 100644
+--- a/tests/clib/test_functions.h
++++ b/tests/clib/test_functions.h
+@@ -79,6 +79,8 @@ extern char *chorse_colour(struct chorse *);
+ extern char *chorse_say(struct animal *);
+ extern char *chorse_identify(struct animal *);
+ extern struct chorse *new_chorse(int);
++extern struct animal *new_chorse_as_animal(int);
++
+ extern int accept_pointers(float *,
+                            double *,
+                            short *,
+diff --git a/tests/test-oo_style/stubs/functions.ml b/tests/test-oo_style/stubs/functions.ml
+index 4434331..6a8e7bd 100644
+--- a/tests/test-oo_style/stubs/functions.ml
++++ b/tests/test-oo_style/stubs/functions.ml
+@@ -82,6 +82,6 @@ struct
+   let check_name = foreign "check_name"
+     (ptr animal @-> string @-> returning int)
+ 
+-    let new_chorse = foreign "new_chorse"
++    let new_chorse = foreign "new_chorse_as_animal"
+       (int @-> returning (ptr animal))
+ end