diff --git a/pkgs/applications/radio/fldigi/default.nix b/pkgs/applications/radio/fldigi/default.nix
index 0de04e26ff36..8650cf59613a 100644
--- a/pkgs/applications/radio/fldigi/default.nix
+++ b/pkgs/applications/radio/fldigi/default.nix
@@ -2,7 +2,7 @@
 , stdenv
 , fetchurl
 , hamlib
-, fltk14
+, fltk13
 , libjpeg
 , libpng
 , portaudio
@@ -31,7 +31,7 @@ stdenv.mkDerivation rec {
     libXinerama
     gettext
     hamlib
-    fltk14
+    fltk13
     libjpeg
     libpng
     portaudio
@@ -39,6 +39,8 @@ stdenv.mkDerivation rec {
     libsamplerate
   ] ++ lib.optionals (stdenv.isLinux) [ libpulseaudio alsa-lib udev ];
 
+  enableParallelBuilding = true;
+
   meta = with lib; {
     description = "Digital modem program";
     homepage = "https://sourceforge.net/projects/fldigi/";