diff 1b594354f7d5dcc28fde2bd15d1b79cb6f1cb3da uncommitted
--- a/sys/src/cmd/ip/ipconfig/ipv6.c
+++ b/sys/src/cmd/ip/ipconfig/ipv6.c
@@ -655,6 +655,7 @@
 		if(m > 100
 		|| r->prefixlt != ~0UL && r->prefixlt < now-r->time
 		|| r->routerlt != ~0UL && r->routerlt < now-r->time
+		|| ipcmp(r->src, ra->src) == 0 && r->prefixlt != 0 && conf.validlt == 0
 		|| ipcmp(r->src, ra->src) == 0 && r->routerlt != 0 && conf.routerlt == 0){
 			DEBUG("purging RA from %I on %s; pfx %I %M",
 				r->src, conf.dev, r->laddr, r->mask);
@@ -715,6 +716,7 @@
 		memmove(r->hash, hash, SHA1dlen);
 
 		if(conf.routerlt == 0
+		|| conf.validlt == 0
 		|| isula(conf.laddr)
 		|| ipcmp(conf.gaddr, conf.laddr) == 0
 		|| ipcmp(conf.gaddr, conf.lladdr) == 0)