--- sys/netinet/in_mcast.c.orig	2008-11-25 02:59:29.000000000 +0000
+++ sys/netinet/in_mcast.c	2009-09-10 23:37:09.000000000 +0000
@@ -1265,6 +1265,9 @@
 		}
 
-		if (gsa->sin.sin_addr.s_addr != INADDR_ANY)
+		if (gsa->sin.sin_addr.s_addr != INADDR_ANY) {
 			INADDR_TO_IFP(mreqs.imr_interface, ifp);
+			if (ifp == NULL)
+				return (EADDRNOTAVAIL);
+		}
 
 #ifdef DIAGNOSTIC