diff --git a/pkgs/development/ocaml-modules/mirage-block/default.nix b/pkgs/development/ocaml-modules/mirage-block/default.nix
index 71ae282ffaca..2194f1183e38 100644
--- a/pkgs/development/ocaml-modules/mirage-block/default.nix
+++ b/pkgs/development/ocaml-modules/mirage-block/default.nix
@@ -7,14 +7,14 @@
   fmt,
 }:
 
-buildDunePackage rec {
+buildDunePackage (finalAttrs: {
   pname = "mirage-block";
   version = "3.0.2";
 
   duneVersion = "3";
 
   src = fetchurl {
-    url = "https://github.com/mirage/mirage-block/releases/download/v${version}/mirage-block-${version}.tbz";
+    url = "https://github.com/mirage/mirage-block/releases/download/v${finalAttrs.version}/mirage-block-${finalAttrs.version}.tbz";
     hash = "sha256-UALUfeL0G1mfSsLgAb/HpQ6OV12YtY+GUOYG6yhUwAI=";
   };
 
@@ -30,4 +30,4 @@ buildDunePackage rec {
     license = lib.licenses.isc;
     maintainers = with lib.maintainers; [ vbgl ];
   };
-}
+})