diff --git a/opam/opam-repository/packages/lablgtk3/lablgtk3.3.1.5/files/0001-fix-pointers.patch b/opam/opam-repository/packages/lablgtk3/lablgtk3.3.1.5/files/0001-fix-pointers.patch
new file mode 100644
index 0000000000..15b4ad1388
--- /dev/null
+++ b/opam/opam-repository/packages/lablgtk3/lablgtk3.3.1.5/files/0001-fix-pointers.patch
@@ -0,0 +1,32 @@
+From 1639f5f14edaf4850fa4f306af38699d982e0621 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Ga=C3=ABtan=20Gilbert?= <gaetan.gilbert@skyskimmer.net>
+Date: Wed, 2 Apr 2025 13:53:27 +0200
+Subject: [PATCH 1/2] Use correct types for custom operations
+
+Fix #188 (hopefully)
+---
+ src/ml_gdkpixbuf.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/src/ml_gdkpixbuf.c b/src/ml_gdkpixbuf.c
+index 51ff2850..64855aa5 100644
+--- a/src/ml_gdkpixbuf.c
++++ b/src/ml_gdkpixbuf.c
+@@ -59,7 +59,7 @@ CAMLprim value ml_gdk_pixbuf_set_marshal_use_rle (value v)
+   return Val_unit;
+ }
+ 
+-static void ml_GdkPixbuf_serialize (value v, unsigned long *wsize_32, unsigned long *wsize_64)
++static void ml_GdkPixbuf_serialize (value v, uintnat *wsize_32, uintnat *wsize_64)
+ {
+   GdkPixbuf *pb = GdkPixbuf_val(v);
+   GdkPixdata pixdata;
+@@ -75,7 +75,7 @@ static void ml_GdkPixbuf_serialize (value v, unsigned long *wsize_32, unsigned l
+   *wsize_64 = 8;
+ }
+ 
+-static unsigned long ml_GdkPixbuf_deserialize (void *dst)
++static uintnat ml_GdkPixbuf_deserialize (void *dst)
+ {
+   GError *error = NULL;
+   GdkPixdata pixdata;
diff --git a/opam/opam-repository/packages/lablgtk3/lablgtk3.3.1.5/opam b/opam/opam-repository/packages/lablgtk3/lablgtk3.3.1.5/opam
new file mode 100644
index 0000000000..2d6ed713a3
--- /dev/null
+++ b/opam/opam-repository/packages/lablgtk3/lablgtk3.3.1.5/opam
@@ -0,0 +1,47 @@
+opam-version: "2.0"
+
+synopsis: "OCaml interface to GTK+3"
+description: """
+OCaml interface to GTK+3
+
+See https://garrigue.github.io/lablgtk/ for more information.
+"""
+
+maintainer: "garrigue@math.nagoya-u.ac.jp"
+authors: ["Jacques Garrigue et al., Nagoya University"]
+homepage: "https://github.com/garrigue/lablgtk"
+bug-reports: "https://github.com/garrigue/lablgtk/issues"
+dev-repo: "git+https://github.com/garrigue/lablgtk.git"
+license: "LGPL-2.1-or-later WITH OCaml-LGPL-linking-exception"
+doc: "https://garrigue.github.io/lablgtk/lablgtk3/lablgtk3"
+
+depends: [
+  "ocaml"     {         >= "4.09.0" }
+  "camlp-streams" {     >= "5.0" & build }
+  "dune"      {         >= "1.8.0"  }
+  "cairo2"    {         >= "0.6"    }
+  "conf-gtk3" {         >= "18"     }
+  "ocamlfind" { dev                 }
+  "camlp5"    { dev                 }
+]
+
+build: [
+  [ "dune" "subst"] {dev}
+  [ "dune" "build" "-p" name "-j" jobs ]
+]
+run-test: [
+  [ "dune" "build" "-p" name "-j" jobs "examples/buttons.exe" ]
+]
+url {
+  src:
+    "https://github.com/garrigue/lablgtk/releases/download/3.1.5/lablgtk3-3.1.5.tbz"
+  checksum: [
+    "sha256=d4821cdbecf3ae374f20317d63e43fe58030c3ba9657b51a2e83e652197e8eac"
+    "sha512=83f0be38a1e21737de93f88b0adac15cdcc50cf712d773720b9bc1e8d8ffdb2c660d35840f25d326a42a9d4e6537e6cef466099bf72494196b2cc79977e703e3"
+  ]
+}
+x-commit-hash: "afbd6d2ee90b98cb0ea49cba34659e15b00cbfe3"
+extra-files: [
+  "0001-fix-pointers.patch"
+  "sha512=56f01d86fede7e43434b14ac85d86c2b90b80594f82f91c41dd4561f042e83d818c42c80f375284aa871180dcef181fcabad0f8c7abff0ed2180790acf5b251f"
+]