diff --git a/include/semaphore.h b/include/semaphore.h
index 218de995392..c42a8d230ec 100644
--- a/include/semaphore.h
+++ b/include/semaphore.h
@@ -36,6 +36,8 @@
 #include <sys/_types.h>
 #include <sys/_umtx.h>
 
+#include <machine/_limits.h>
+
 struct _sem {
 	__uint32_t	_magic;
 	struct _usem2	_kern;