diff --git a/sbin/comcontrol/Makefile b/sbin/comcontrol/Makefile
index d8757565b1a0..a7720d81b41e 100644
--- a/sbin/comcontrol/Makefile
+++ b/sbin/comcontrol/Makefile
@@ -3,5 +3,6 @@
 
 PROG=	comcontrol
 MAN=	comcontrol.8
+WARNS?=	6
 
 .include <bsd.prog.mk>
diff --git a/sbin/comcontrol/comcontrol.c b/sbin/comcontrol/comcontrol.c
index 302d5e67c650..753ded36d1a9 100644
--- a/sbin/comcontrol/comcontrol.c
+++ b/sbin/comcontrol/comcontrol.c
@@ -40,6 +40,8 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/ioctl.h>
 
+static void usage(void);
+
 static void
 usage()
 {