diff --git a/pkgs/os-specific/darwin/by-name/co/copyfile/package.nix b/pkgs/os-specific/darwin/by-name/co/copyfile/package.nix
index 413e6532b3a6..f76e5beaa766 100644
--- a/pkgs/os-specific/darwin/by-name/co/copyfile/package.nix
+++ b/pkgs/os-specific/darwin/by-name/co/copyfile/package.nix
@@ -1,12 +1,11 @@
 {
-  lib,
-  apple-sdk,
   mkAppleDerivation,
+  sourceRelease,
   stdenvNoCC,
 }:
 
 let
-  xnu = apple-sdk.sourceRelease "xnu";
+  xnu = sourceRelease "xnu";
 
   privateHeaders = stdenvNoCC.mkDerivation {
     name = "copyfile-deps-private-headers";