diff --git a/src/tcpcheck.c b/src/tcpcheck.c
index ce82ea507..0e7930dfc 100644
--- a/src/tcpcheck.c
+++ b/src/tcpcheck.c
@@ -1399,7 +1399,9 @@ enum tcpcheck_eval_ret tcpcheck_eval_connect(struct check *check, struct tcpchec
 	*conn->dst = (is_addr(&connect->addr)
 		      ? connect->addr
 		      : (is_addr(&check->addr) ? check->addr : s->addr));
-	proto = protocol_lookup(conn->dst->ss_family, PROTO_TYPE_STREAM, 0);
+	proto = s ?
+	  protocol_lookup(conn->dst->ss_family, s->addr_type.proto_type, s->alt_proto) :
+	  protocol_lookup(conn->dst->ss_family, PROTO_TYPE_STREAM, 0);
 
 	port = 0;
 	if (connect->port)