diff --git a/dbms/src/Processors/Merges/AggregatingSortedTransform.cpp b/dbms/src/Processors/Merges/AggregatingSortedTransform.cpp
index 23524dfc395..1c94bca4e3a 100644
--- a/dbms/src/Processors/Merges/AggregatingSortedTransform.cpp
+++ b/dbms/src/Processors/Merges/AggregatingSortedTransform.cpp
@@ -60,6 +60,8 @@ namespace
                 def.columns_to_aggregate.emplace_back(i);
             }
         }
+
+        return def;
     }
 }