diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index eda273176794..b83e5809912b 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -28,6 +28,7 @@
 __FBSDID("$FreeBSD$");
 
 #include "opt_capsicum.h"
+#include "opt_compat.h"
 #include "opt_hwpmc_hooks.h"
 #include "opt_ktrace.h"
 #include "opt_vm.h"