diff --git a/tests/sys/netinet/libalias/perf.c b/tests/sys/netinet/libalias/perf.c
index e8de1e715013..b9e95a25b617 100644
--- a/tests/sys/netinet/libalias/perf.c
+++ b/tests/sys/netinet/libalias/perf.c
@@ -38,6 +38,8 @@
 #include "util.h"
 #include <alias.h>
 
+static void usage(void);
+
 #define	timevalcmp(tv, uv, cmp)			\
 	(((tv).tv_sec == (uv).tv_sec)		\
 	 ? ((tv).tv_usec cmp (uv).tv_usec)	\