{ pngSupport ? true
, stdenv, fetchurl, x11, libpng ? null}:

assert x11 != null;
assert pngSupport -> libpng != null;

derivation {
  name = "zvbi-0.2.5";
  system = stdenv.system;
  builder = ./builder.sh;
  src = fetchurl {
    url = http://heanet.dl.sourceforge.net/sourceforge/zapping/zvbi-0.2.5.tar.bz2;
    md5 = "06b370565246758813f6580797369518";
  };
  stdenv = stdenv;
  x11 = x11;
  pngSupport = pngSupport;
  libpng = if pngSupport then libpng else null;
}