diff --git a/pkgs/development/ocaml-modules/uchar/default.nix b/pkgs/development/ocaml-modules/uchar/default.nix
index a482a7e0a75f..645532447de6 100644
--- a/pkgs/development/ocaml-modules/uchar/default.nix
+++ b/pkgs/development/ocaml-modules/uchar/default.nix
@@ -9,12 +9,12 @@
   lib,
 }:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation (finalAttrs: {
   pname = "ocaml${ocaml.version}-uchar";
   version = "0.0.2";
 
   src = fetchurl {
-    url = "https://github.com/ocaml/uchar/releases/download/v${version}/uchar-${version}.tbz";
+    url = "https://github.com/ocaml/uchar/releases/download/v${finalAttrs.version}/uchar-${finalAttrs.version}.tbz";
     hash = "sha256-Rzl/MWy+diNK9Tx0oflFIVS6O9tU/O1cqslZ9Q9XWvA=";
   };
 
@@ -35,4 +35,4 @@ stdenv.mkDerivation rec {
     inherit (ocaml.meta) platforms license;
     maintainers = [ lib.maintainers.vbgl ];
   };
-}
+})