1 files changed, 1 insertions, 0 deletions
diff --git a/sql/item_sum.h b/sql/item_sum.h
index 11c95100db5..41d700b0ff8 100644
--- a/sql/item_sum.h
+++ b/sql/item_sum.h
@@ -533,6 +533,7 @@ public:
   const char *func_name() const { return udf.name(); }
   bool fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
   {
+    DBUG_ASSERT(fixed == 0);
     fixed= 1;
     return udf.fix_fields(thd,tables,this,this->arg_count,this->args);
   }