Index: sys/netinet6/in6_ifattach.c
===================================================================
--- sys/netinet6/in6_ifattach.c
+++ sys/netinet6/in6_ifattach.c
@@ -520,8 +520,11 @@
 	 * valid with referring to the old link-local address.
 	 */
 	if ((pr = nd6_prefix_lookup(&pr0)) == NULL) {
-		if ((error = nd6_prelist_add(&pr0, NULL, NULL)) != 0)
+		if ((error = nd6_prelist_add(&pr0, NULL, &pr)) != 0)
 			return (error);
+		/* Reference prefix */
+		ia->ia6_ndpr = pr;
+		pr->ndpr_addrcnt++;
 	} else
 		nd6_prefix_rele(pr);