diff --git a/libraries/zmusic/mididevices/music_fluidsynth_mididevice.cpp b/libraries/zmusic/mididevices/music_fluidsynth_mididevice.cpp
index fee61bcb7..b811277e5 100644
--- a/libraries/zmusic/mididevices/music_fluidsynth_mididevice.cpp
+++ b/libraries/zmusic/mididevices/music_fluidsynth_mididevice.cpp
@@ -36,6 +36,7 @@
 
 #include <mutex>
 #include <stdio.h>
+#include <stdlib.h>
 #include "mididevice.h"
 #include "zmusic/mus2midi.h"