diff --git a/server/gameserver/custom_battle.cc b/server/gameserver/custom_battle.cc
index 205ac1f9..f5be5a55 100644
--- a/server/gameserver/custom_battle.cc
+++ b/server/gameserver/custom_battle.cc
@@ -81,6 +81,12 @@ void CustomBattle::ParseResult(a8::XObject& obj)
 bool CustomBattle::CanAdd(const std::string& account_id, const std::string& session_id)
 {
     auto member = GetMemberByAccountId(account_id);
+    if (!member) {
+        return false;
+    }
+    if (member->IsJoined()) {
+        return false;
+    }
     return true;
 }