diff --git a/sys/sys/kassert.h b/sys/sys/kassert.h
--- a/sys/sys/kassert.h
+++ b/sys/sys/kassert.h
@@ -31,6 +31,7 @@
 #ifndef _SYS_KASSERT_H_
 #define	_SYS_KASSERT_H_
 
+#include <sys/_types.h>
 #include <sys/cdefs.h>
 
 #ifdef _KERNEL