gistfile1.txt

  nixpkgs.config.packageOverrides = pkgs: with pkgs; {
    virtualboxGuestAdditions = stdenv.lib.overrideDerivation pkgs.virtualboxGuestAdditions (oldAttrs: {
      version = "4.3.13-94438";
      src = fetchurl {
        url = https://www.virtualbox.org/download/testcase/VBoxGuestAdditions_4.3.13-94438.iso;
        sha256 = "02i1405v4zdi293bipd3rjbp7a1z65yjgyfzn10iy0s84gfz8ij0";
      };
    });
  };