diff --git a/sys/kern/kern_lock.c b/sys/kern/kern_lock.c
index 9710b8e98017..7e8a55bbfa32 100644
--- a/sys/kern/kern_lock.c
+++ b/sys/kern/kern_lock.c
@@ -40,6 +40,7 @@
 #include <sys/param.h>
 #include <sys/proc.h>
 #include <sys/lock.h>
+#include <sys/systm.h>
 #include <machine/cpu.h>
 
 /*