diff --git a/t-mysql-server/sql/item_sum.cc b/t-mysql-server/sql/item_sum.cc
index 4713629..11627d3 100644
--- a/t-mysql-server/sql/item_sum.cc
+++ b/t-mysql-server/sql/item_sum.cc
@@ -1103,6 +1103,9 @@ void Aggregator_distinct::endup()
       sum->count= table->file->stats.records;
       endup_done= TRUE;
     }
+
+    if (!endup_done)
+      sum->args[0]->maybe_null= 0;
   }
   else
   {