diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 919de682b331..55ea80fac601 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1983,9 +1983,10 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg)
 	    !dst_metric_locked(&rt->u.dst, RTAX_MTU) &&
 	    (dst_mtu(&rt->u.dst) > arg->mtu ||
 	     (dst_mtu(&rt->u.dst) < arg->mtu &&
-	      dst_mtu(&rt->u.dst) == idev->cnf.mtu6)))
+	      dst_mtu(&rt->u.dst) == idev->cnf.mtu6))) {
 		rt->u.dst.metrics[RTAX_MTU-1] = arg->mtu;
-	rt->u.dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(arg->mtu);
+		rt->u.dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(arg->mtu);
+	}
 	return 0;
 }