--- ../../wide-dhcpv6/prefixconf.c	2006-08-07 13:35:32.000000000 +0900
+++ prefixconf.c	2006-11-05 00:15:21.000000000 +0900
@@ -452,6 +452,7 @@
 #endif
 	ifpfx->paddr.sin6_addr = prefix->addr;
 	ifpfx->plen = prefix->plen + pconf->sla_len;
+
 	/*
 	 * XXX: our current implementation assumes ifid len is a multiple of 8
 	 */
@@ -467,6 +468,7 @@
 			prefix->plen, pconf->sla_len, pconf->ifid_len);
 		goto bad;
 	}
+	
 
 	/* copy prefix and SLA ID */
 	a = &ifpfx->paddr.sin6_addr;
@@ -483,8 +485,18 @@
 
 	/* configure the corresponding address */
 	ifpfx->ifaddr = ifpfx->paddr;
-	for (i = 15; i >= pconf->ifid_len / 8; i--)
-		ifpfx->ifaddr.sin6_addr.s6_addr[i] = pconf->ifid[i];
+
+	if (prefix->plen == 64) {
+		for (i = 8; i > 15; i++) {
+			ifpfx->ifaddr.sin6_addr.s6_addr[i] = 0;
+		}
+		ifpfx->ifaddr.sin6_addr.s6_addr[15] = 1;
+	} else {
+		for (i = 15; i >= pconf->ifid_len / 8; i--) {
+			ifpfx->ifaddr.sin6_addr.s6_addr[i] = pconf->ifid[i];
+		}
+	}
+
 	if (pd_ifaddrconf(IFADDRCONF_ADD, ifpfx))
 		goto bad;