Index: head/sys/netinet/in_mcast.c
===================================================================
--- head/sys/netinet/in_mcast.c
+++ head/sys/netinet/in_mcast.c
@@ -344,12 +344,13 @@
 
 	inm = NULL;
 	TAILQ_FOREACH(ifma, &((ifp)->if_multiaddrs), ifma_link) {
-		if (ifma->ifma_addr->sa_family == AF_INET) {
-			inm = (struct in_multi *)ifma->ifma_protospec;
-			if (inm->inm_addr.s_addr == ina.s_addr)
-				break;
-			inm = NULL;
-		}
+		if (ifma->ifma_addr->sa_family != AF_INET ||
+		    ifma->ifma_protospec == NULL)
+			continue;
+		inm = (struct in_multi *)ifma->ifma_protospec;
+		if (inm->inm_addr.s_addr == ina.s_addr)
+			break;
+		inm = NULL;
 	}
 	return (inm);
 }