optimization_find_dup_table

diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index c5510d9..87e6788 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -1337,6 +1337,9 @@ TABLE_LIST* find_dup_table(THD *thd, TABLE_LIST *table, TABLE_LIST *table_list,
   DBUG_ENTER("find_dup_table");
   DBUG_PRINT("enter", ("table alias: %s", table->alias));
 
+  if (table_list == 0)
+    DBUG_RETURN(0);
+
   /*
     If this function called for query which update table (INSERT/UPDATE/...)
     then we have in table->table pointer to TABLE object which we are