diff --git a/miniupnpd/netfilter/iptpinhole.c b/miniupnpd/netfilter/iptpinhole.c
index 61ed41b..5cb0e0e 100644
--- a/miniupnpd/netfilter/iptpinhole.c
+++ b/miniupnpd/netfilter/iptpinhole.c
@@ -206,6 +206,8 @@ int add_pinhole(const char * ifname,
 
 	e = calloc(1, sizeof(struct ip6t_entry));
 	e->ipv6.proto = proto;
+	if (proto)
+		e->ipv6.flags |= IP6T_F_PROTO;
 
 	if(ifname)
 		strncpy(e->ipv6.iniface, ifname, IFNAMSIZ);