--- kernel/bsd/netiso/iso_snpac.c	2018/04/24 18:26:01	1.1
+++ kernel/bsd/netiso/iso_snpac.c	2018/04/24 18:28:53	1.1.1.2
@@ -576,7 +576,7 @@ register struct rtentry *sc;
 		RTFREE(known_is);
 	}
 	known_is = sc;
-	sc->rt_refcnt++;
+	RTHOLD(sc);
 	rt = rtalloc1((struct sockaddr *)&zsi, 0);
 	if (rt == 0)
 		rtrequest(RTM_ADD, S(zsi), rt_key(sc), S(zmk),