diff --git a/v2ray_util/util_core/group.py b/v2ray_util/util_core/group.py
index c340e33b..962684ab 100644
--- a/v2ray_util/util_core/group.py
+++ b/v2ray_util/util_core/group.py
@@ -269,7 +269,7 @@ def __str__(self):
         port_way = "-{}".format(self.end_port) if self.end_port else ""
         if self.tls == "tls":
             tls = _("open")
-            if self.node_list[0].flow:
+            if hasattr(self.node_list[0], "flow"):
                 tls += " flow: {}".format(self.node_list[0].flow)
         elif self.tls == "reality":
             tls = "reality serverName: {0}, flow: {1}, publicKey: {2}, shortId: {3}".format(self.node_list[0].serverName, self.node_list[0].flow, x25519_key(self.node_list[0].privateKey)[1], self.node_list[0].shortId)