Index: sys/kern/subr_witness.c
===================================================================
--- sys/kern/subr_witness.c
+++ sys/kern/subr_witness.c
@@ -111,6 +111,8 @@
 #include <sys/syslog.h>
 #include <sys/systm.h>
 
+FEATURE(witness, "kernel has WITNESS support");
+
 #ifdef DDB
 #include <ddb/ddb.h>
 #endif