--- net_udp.c.orig	Thu Jan 27 19:15:55 2000
+++ net_udp.c	Thu Jan 27 19:16:59 2000
@@ -63,6 +63,11 @@
 #define INADDR_NONE 0xffffffff
 #endif
 
+#if !defined(IPV6_ADD_MEMBERSHIP) && defined(IPV6_JOIN_GROUP)
+#define	IPV6_ADD_MEMBERSHIP	IPV6_JOIN_GROUP
+#define	IPV6_DROP_MEMBERSHIP	IPV6_LEAVE_GROUP
+#endif
+
 struct _socket_udp {
 	int	 	 mode;	/* IPv4 or IPv6 */
 	char		*addr;