diff --git a/sys/sys/ktrace.h b/sys/sys/ktrace.h
index 110e1469857..594f912b02e 100644
--- a/sys/sys/ktrace.h
+++ b/sys/sys/ktrace.h
@@ -336,8 +336,10 @@ void	ktrcapfail(enum ktr_cap_fail_type, const cap_rights_t *,
 extern u_int ktr_geniosize;
 #ifdef	KTRACE
 extern int ktr_filesize_limit_signal;
+#define	__ktrace_used
 #else
 #define	ktr_filesize_limit_signal 0
+#define	__ktrace_used	__unused
 #endif
 #else