diff --git a/sys/kern/tty_info.c b/sys/kern/tty_info.c
index 378e1bc64284..78c42f1c9c79 100644
--- a/sys/kern/tty_info.c
+++ b/sys/kern/tty_info.c
@@ -45,6 +45,8 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include "opt_stack.h"
+
 #include <sys/param.h>
 #include <sys/cons.h>
 #include <sys/kdb.h>