diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 7403d90dcb38..1b57e11e6e0d 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2761,6 +2761,7 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg)
 	   PMTU discouvery.
 	 */
 	if (rt->dst.dev == arg->dev &&
+	    dst_metric_raw(&rt->dst, RTAX_MTU) &&
 	    !dst_metric_locked(&rt->dst, RTAX_MTU)) {
 		if (rt->rt6i_flags & RTF_CACHE) {
 			/* For RTF_CACHE with rt6i_pmtu == 0