--- sys/netinet/in_mcast.c.orig	2009-09-08 16:09:46.000000000 +0000
+++ sys/netinet/in_mcast.c	2009-09-10 23:27:14.000000000 +0000
@@ -1137,5 +1142,5 @@
 				 * already an ASM member) is an error.
 				 */
-				error = EINVAL;
+				error = EADDRINUSE;
 			} else {
 				/*