diff --git a/sys/net/if_arcsubr.c b/sys/net/if_arcsubr.c
index 6205117ba85..d6724cf65ea 100644
--- a/sys/net/if_arcsubr.c
+++ b/sys/net/if_arcsubr.c
@@ -167,7 +167,7 @@ arc_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
 #endif
 #ifdef INET6
 	case AF_INET6:
-		if ((m->m_flags & M_MCAST) != NULL)
+		if ((m->m_flags & M_MCAST) != 0)
 			adst = arcbroadcastaddr; /* ARCnet broadcast address */
 		else
 			error = nd6_storelladdr(ifp, m, dst, (u_char *)&adst, NULL);