anchor.diff: -{ lib, stdenv, SDL, fetchurl, gzip, libvorbis, libmad }:
  +{ lib, stdenv, SDL, fetchurl, gzip, libvorbis, libmad, copyDesktopItems, makeDesktopItem }:
   
   stdenv.mkDerivation rec {
     pname = "quakespasm";
  
positive.code:   '';
  
    enableParallelBuilding = true;
  
    meta = with lib; {
      description = "An engine for iD software's Quake";
  
negative.code: 
    sourceRoot = "${pname}-${version}/Quake";
  
    nativeBuildInputs = [ copyDesktopItems ];
    buildInputs = [
      gzip SDL libvorbis libmad
    ];
  