anchor.diff:    '';
   
     buildInputs = [
  -    openssl libuuid libwebsockets c-ares libuv
  +    openssl libuuid libwebsockets_3_1 c-ares libuv
     ] ++ lib.optional withSystemd systemd;
   
     nativeBuildInputs = [ cmake docbook_xsl libxslt ];
  
positive.code: 
    meta = with stdenv.lib; {
      description = "An open source MQTT v3.1/3.1.1 broker";
      homepage = http://mosquitto.org/;
      license = licenses.epl10;
      maintainers = with maintainers; [ peterhoeg ];
      platforms = platforms.unix;
  
negative.code: { stdenv, lib, fetchFromGitHub, cmake, docbook_xsl, libxslt
  , openssl, libuuid, libwebsockets_3_1, c-ares, libuv
  , systemd ? null, withSystemd ? stdenv.isLinux }:
  
  stdenv.mkDerivation rec {
    pname = "mosquitto";
    version = "1.6.5";
  
    src = fetchFromGitHub {
      owner  = "eclipse";
      repo   = "mosquitto";
      rev    = "v${version}";
      sha256 = "0scgsi3rvs9s8vxv4r7d5d9ixbsfg4dwnjcy6zxwdz9dfn8qnngj";
    };
  
    postPatch = ''
  