diff --git a/pkgs/development/ocaml-modules/duration/default.nix b/pkgs/development/ocaml-modules/duration/default.nix
index 137edf6f8d2a..ba42a8b3af17 100644
--- a/pkgs/development/ocaml-modules/duration/default.nix
+++ b/pkgs/development/ocaml-modules/duration/default.nix
@@ -6,14 +6,14 @@
   alcotest,
 }:
 
-buildDunePackage rec {
+buildDunePackage (finalAttrs: {
   pname = "duration";
   version = "0.2.1";
 
   duneVersion = "3";
 
   src = fetchurl {
-    url = "https://github.com/hannesm/duration/releases/download/v${version}/duration-${version}.tbz";
+    url = "https://github.com/hannesm/duration/releases/download/v${finalAttrs.version}/duration-${finalAttrs.version}.tbz";
     hash = "sha256-xzjB84z7mYIMEhzT3fgZ3ksiKPDVDqy9HMPOmefHHis=";
   };
 
@@ -27,4 +27,4 @@ buildDunePackage rec {
     maintainers = [ lib.maintainers.vbgl ];
   };
 
-}
+})