diff --git a/sql/item_timefunc.cc b/sql/item_timefunc.cc
index d060612c9f6b37bd293beab280f288bebdd8cc40..be8c5d2ad155cb722f57ec5326962cbbfdf55033 100644
--- a/sql/item_timefunc.cc
+++ b/sql/item_timefunc.cc
@@ -2750,7 +2750,8 @@ void Item_func_str_to_date::fix_length_and_dec()
   cached_field_type= MYSQL_TYPE_STRING;
   max_length= MAX_DATETIME_FULL_WIDTH*MY_CHARSET_BIN_MB_MAXLEN;
   cached_timestamp_type= MYSQL_TIMESTAMP_NONE;
-  if ((const_item= args[1]->const_item()) && !args[1]->null_value)
+  if (!args[1]->null_value && (const_item= args[1]->const_item()))
+  //if ((const_item= args[1]->const_item()) && !args[1]->null_value)
   {
     format= args[1]->val_str(&format_str);
     cached_format_type= get_date_time_result_type(format->ptr(),