diff --git a/usr.sbin/arp/Makefile b/usr.sbin/arp/Makefile
index ea1c507debc7..829367a770ff 100644
--- a/usr.sbin/arp/Makefile
+++ b/usr.sbin/arp/Makefile
@@ -4,6 +4,6 @@
 PROG=	arp
 MAN=	arp.4 arp.8
 
-WARNS?=	1
+WARNS?=	6
 
 .include <bsd.prog.mk>
diff --git a/usr.sbin/arp/arp.c b/usr.sbin/arp/arp.c
index f99cf0f89350..e585ba0fecd9 100644
--- a/usr.sbin/arp/arp.c
+++ b/usr.sbin/arp/arp.c
@@ -721,9 +721,13 @@ rtmsg(int cmd, struct sockaddr_inarp *dst, struct sockaddr_dl *sdl)
 	case RTM_GET:
 		rtm->rtm_addrs |= RTA_DST;
 	}
-#define NEXTADDR(w, s) \
-	if ((s) != NULL && rtm->rtm_addrs & (w)) { \
-		bcopy((s), cp, sizeof(*(s))); cp += SA_SIZE(s);}
+#define NEXTADDR(w, s)					   \
+	do {						   \
+		if ((s) != NULL && rtm->rtm_addrs & (w)) { \
+			bcopy((s), cp, sizeof(*(s)));	   \
+			cp += SA_SIZE(s);		   \
+		}					   \
+	} while (0)
 
 	NEXTADDR(RTA_DST, dst);
 	NEXTADDR(RTA_GATEWAY, sdl);