# Pastebin FFBCp4JY
    gemConfig = defaultGemConfig // {
      opus-ruby = attrs: {
        dontBuild = false;
        postPatch = ''
          substituteInPlace lib/opus-ruby.rb \
            --replace "ffi_lib 'opus'" \
                      "ffi_lib '${libopus}/lib/libopus${stdenv.hostPlatform.extensions.sharedLibrary}'"
        '';
      };
    };