anchor.diff:      mkdir -p $out/lib
     '';
   
  -  buildInputs = [ libGLU libGL libXrandr libX11 libXxf86vm ];
  +  buildInputs = [ libGLU libGL libXrandr libX11 libXxf86vm ]
  +                ++ lib.optional stdenv.isAarch64 zlib;
   
     meta = {
       homepage = "http://irrlicht.sourceforge.net/";
  
positive.code: { lib, stdenv, fetchzip, libGLU, libGL, libXrandr, libX11, libXxf86vm }:
  
  let
    common = import ./common.nix { inherit fetchzip; };
  
negative.code: 
    postPatch = ''
      sed -ie '/sys\/sysctl.h/d' source/Irrlicht/COSOperator.cpp
    '' + lib.optionalString stdenv.isAarch64 ''
      substituteInPlace source/Irrlicht/Makefile \
        --replace "-DIRRLICHT_EXPORTS=1" "-DIRRLICHT_EXPORTS=1 -DPNG_ARM_NEON_OPT=0"
    '';
  
    preConfigure = ''
  