diff --git a/lib/synch.h b/lib/synch.h
index dd2abad216..c482f05f76 100644
--- a/lib/synch.h
+++ b/lib/synch.h
@@ -1,3 +1,4 @@
+#include <sys/types.h>
 #include <sys/sem.h>
 #include <sys/ipc.h>