diff --git a/pkgs/development/ocaml-modules/saturn/lockfree.nix b/pkgs/development/ocaml-modules/saturn/lockfree.nix
index 538dfda5e838..bfa91f76f7ea 100644
--- a/pkgs/development/ocaml-modules/saturn/lockfree.nix
+++ b/pkgs/development/ocaml-modules/saturn/lockfree.nix
@@ -6,14 +6,14 @@
   multicore-magic,
 }:
 
-buildDunePackage rec {
+buildDunePackage (finalAttrs: {
   pname = "saturn_lockfree";
   version = "0.5.0";
 
   minimalOCamlVersion = "4.13";
 
   src = fetchurl {
-    url = "https://github.com/ocaml-multicore/saturn/releases/download/${version}/saturn-${version}.tbz";
+    url = "https://github.com/ocaml-multicore/saturn/releases/download/${finalAttrs.version}/saturn-${finalAttrs.version}.tbz";
     hash = "sha256-ZmmxwIe5PiPYTTdvOHbOjRbv2b/bb9y0IekByfREPjk=";
   };
 
@@ -28,4 +28,4 @@ buildDunePackage rec {
     license = lib.licenses.isc;
     maintainers = [ lib.maintainers.vbgl ];
   };
-}
+})