diff --git a/source/os/src/osSemaphore.c b/source/os/src/osSemaphore.c
index 5da78f002f..c57ea33028 100644
--- a/source/os/src/osSemaphore.c
+++ b/source/os/src/osSemaphore.c
@@ -16,6 +16,7 @@
 #define ALLOW_FORBID_FUNC
 #define _DEFAULT_SOURCE
 #include "os.h"
+#include "tdef.h"
 #include "pthread.h"
 
 #ifdef WINDOWS