diff --git a/src/checks.c b/src/checks.c
index 35744c6b7..31004ddf8 100644
--- a/src/checks.c
+++ b/src/checks.c
@@ -2839,7 +2839,7 @@ static int tcpcheck_main(struct check *check)
 			cs_attach(cs, check, &check_conn_cb);
 
 			ret = SF_ERR_INTERNAL;
-			if (proto->connect)
+			if (proto && proto->connect)
 				ret = proto->connect(conn,
 						     1 /* I/O polling is always needed */,
 						     (next && next->action == TCPCHK_ACT_EXPECT) ? 0 : 2);