diff --git a/pkgs/development/ocaml-modules/hex/default.nix b/pkgs/development/ocaml-modules/hex/default.nix
index 1d7850b96b03..b6cc694d578c 100644
--- a/pkgs/development/ocaml-modules/hex/default.nix
+++ b/pkgs/development/ocaml-modules/hex/default.nix
@@ -5,7 +5,7 @@
   cstruct,
 }:
 
-buildDunePackage rec {
+buildDunePackage (finalAttrs: {
   pname = "hex";
   version = "1.5.0";
 
@@ -13,7 +13,7 @@ buildDunePackage rec {
   minimalOCamlVersion = "4.08";
 
   src = fetchurl {
-    url = "https://github.com/mirage/ocaml-${pname}/releases/download/v${version}/hex-${version}.tbz";
+    url = "https://github.com/mirage/ocaml-hex/releases/download/v${finalAttrs.version}/hex-${finalAttrs.version}.tbz";
     hash = "sha256-LmfuyhsDBJMHowgxtc1pS8stPn8qa0+1l/vbZHNRtNw=";
   };
 
@@ -26,4 +26,4 @@ buildDunePackage rec {
     license = lib.licenses.isc;
     maintainers = with lib.maintainers; [ vbgl ];
   };
-}
+})