diff --git a/pkgs/development/ocaml-modules/piaf/default.nix b/pkgs/development/ocaml-modules/piaf/default.nix
index dae4a95291d0..780b5c7ecc0b 100644
--- a/pkgs/development/ocaml-modules/piaf/default.nix
+++ b/pkgs/development/ocaml-modules/piaf/default.nix
@@ -21,12 +21,12 @@
   eio_main,
 }:
 
-buildDunePackage rec {
+buildDunePackage (finalAttrs: {
   pname = "piaf";
   version = "0.2.0";
 
   src = fetchurl {
-    url = "https://github.com/anmonteiro/piaf/releases/download/${version}/piaf-${version}.tbz";
+    url = "https://github.com/anmonteiro/piaf/releases/download/${finalAttrs.version}/piaf-${finalAttrs.version}.tbz";
     hash = "sha256-B/qQCaUvrqrm2GEW51AH9SebGFx7x8laq5RV8hBzcPs=";
   };
 
@@ -60,4 +60,4 @@ buildDunePackage rec {
     license = lib.licenses.bsd3;
     maintainers = with lib.maintainers; [ anmonteiro ];
   };
-}
+})