diff --git a/src/lib/portmidi/ptmacosx_mach.c b/src/lib/portmidi/ptmacosx_mach.c
index d477e56e771..81832602bf2 100644
--- a/src/lib/portmidi/ptmacosx_mach.c
+++ b/src/lib/portmidi/ptmacosx_mach.c
@@ -14,7 +14,9 @@
 #include "sys/time.h"
 #include "pthread.h"
 
-//#define NSEC_PER_MSEC 1000000
+#if !defined NSEC_PER_MSEC
+#define NSEC_PER_MSEC 1000000ull
+#endif
 #define THREAD_IMPORTANCE 30
 
 static int time_started_flag = FALSE;