diff --git a/pkgs/by-name/pr/prototypejs/package.nix b/pkgs/by-name/pr/prototypejs/package.nix
index 9ac7a68943b3..d9db3009327a 100644
--- a/pkgs/by-name/pr/prototypejs/package.nix
+++ b/pkgs/by-name/pr/prototypejs/package.nix
@@ -1,10 +1,10 @@
 { lib, fetchurl, ... }:
-let
+fetchurl (finalAttrs: {
+  pname = "prototype";
   version = "1.7.3.0";
-in
-fetchurl {
-  name = "prototype-${version}.js";
-  url = "https://ajax.googleapis.com/ajax/libs/prototype/${version}/prototype.js";
+  name = "${finalAttrs.pname}-${finalAttrs.version}.js";
+
+  url = "https://ajax.googleapis.com/ajax/libs/prototype/${finalAttrs.version}/prototype.js";
   sha256 = "0q43vvrsb22h4jvavs1gk3v4ps61yx9k85b5n6q9mxivhmxprg26";
 
   meta = {
@@ -21,4 +21,4 @@ fetchurl {
     license = lib.licenses.mit;
     maintainers = with lib.maintainers; [ das_j ];
   };
-}
+})