diff --git a/dbms/src/AggregateFunctions/AggregateFunctionWindowFunnel.h b/dbms/src/AggregateFunctions/AggregateFunctionWindowFunnel.h
index 391f6f7d527..e8668b6172e 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionWindowFunnel.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionWindowFunnel.h
@@ -56,6 +56,9 @@ struct AggregateFunctionWindowFunnelData
 
     void merge(const AggregateFunctionWindowFunnelData & other)
     {
+        if (other.events_list.empty())
+            return;
+
         const auto size = events_list.size();
 
         events_list.insert(std::begin(other.events_list), std::end(other.events_list));