diff --git a/sys/kern/kern_lock.c b/sys/kern/kern_lock.c
index 12c0d9c02382..0004298586cc 100644
--- a/sys/kern/kern_lock.c
+++ b/sys/kern/kern_lock.c
@@ -44,6 +44,7 @@
 __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
+#include <sys/kdb.h>
 #include <sys/kernel.h>
 #include <sys/ktr.h>
 #include <sys/lock.h>