anchor.diff:      
       # Install Xorg drivers
       ensureDir $out/lib/xorg/modules/{drivers,input}
  -    install -m 644 lib/VBoxGuestAdditions/vboxvideo_drv_17.so $out/lib/xorg/modules/drivers/vboxvideo_drv.so
  -    install -m 644 lib/VBoxGuestAdditions/vboxmouse_drv_17.so $out/lib/xorg/modules/input/vboxmouse_drv.so
  +    install -m 644 lib/VBoxGuestAdditions/vboxvideo_drv_18.so $out/lib/xorg/modules/drivers/vboxvideo_drv.so
  +    install -m 644 lib/VBoxGuestAdditions/vboxmouse_drv_18.so $out/lib/xorg/modules/input/vboxmouse_drv.so
       
       # Install kernel modules
       cd src
  
positive.code: { stdenv, fetchurl, lib, patchelf, cdrkit, kernel
  , libX11, libXt, libXext, libXmu, libXcomposite, libXfixes}:
  
  stdenv.mkDerivation {
    name = "VirtualBox-GuestAdditions-3.1.8";
    src = fetchurl {
      url = http://download.virtualbox.org/virtualbox/3.1.8/VBoxGuestAdditions_3.1.8.iso;
      sha256 = "11fn49zxmd7nxmqn9pcakmzj6j9f8kfb38czpl8fhbnl2k4ggj5q";
    };
    KERN_DIR = "${kernel}/lib/modules/*/build";
    buildInputs = [ patchelf cdrkit ];
  
negative.code:     done
  
      # Change rpath for various binaries and libraries
      patchelf --set-rpath ${stdenv.gcc.gcc}/lib:${libX11}/lib:${libXt}/lib:${libXext}/lib:${libXmu}/lib:${libXfixes}/lib:${libXrandr}/lib:${libXcursor}/lib bin/VBoxClient
  
      for i in lib/VBoxOGL*.so
      do
  