anchor.diff:      ++ opt clientSupport mpd_clientlib
       ++ opt opusSupport libopus
       ++ opt soundcloudSupport yajl;
  +
  +  nativeBuildInputs = [ autoreconfHook pkgconfig ];
  +
  +  enableParallelBuilding = true;
   
     configureFlags =
       [ (mkFlag (!stdenv.isDarwin && alsaSupport) "alsa")
  
positive.code:   opt = stdenv.lib.optional;
    mkFlag = c: f: if c then "--enable-${f}" else "--disable-${f}";
    major = "0.20";
    minor = "6";
  
  in stdenv.mkDerivation rec {
    name = "mpd-${major}${if minor == "" then "" else "." + minor}";
    src = fetchurl {
      url    = "http://www.musicpd.org/download/mpd/${major}/${name}.tar.xz";
      sha256 = "0isbpa79m7zf09w3s1ry638cw96rxasy1ch66zl01k75i48mw1gl";
    };
  
    patches = [ ./x86.patch ];
  
    buildInputs = [ pkgconfig glib boost ]
      ++ opt stdenv.isDarwin darwin.apple_sdk.frameworks.CoreAudioKit
      ++ opt stdenv.isLinux systemd
      ++ opt (stdenv.isLinux && alsaSupport) alsaLib
  
negative.code: { stdenv, fetchFromGitHub, fetchpatch, autoreconfHook, pkgconfig, glib, systemd, boost, darwin
  , alsaSupport ? true, alsaLib
  , avahiSupport ? true, avahi, dbus
  , flacSupport ? true, flac
  