diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 823e3ed88bf..c360796132d 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -17823,12 +17823,12 @@ create_tmp_table(THD *thd, TMP_TABLE_PARAM *param, List<Item> &fields,
     temp_pool_slot = bitmap_lock_set_next(&temp_pool);
 
   if (temp_pool_slot != MY_BIT_NONE) // we got a slot
-    sprintf(path, "%s_%lx_%i", tmp_file_prefix,
+    sprintf(path, "%s-%lx-%i", tmp_file_prefix,
             current_pid, temp_pool_slot);
   else
   {
     /* if we run out of slots or we are not using tempool */
-    sprintf(path, "%s%lx_%lx_%x", tmp_file_prefix,current_pid,
+    sprintf(path, "%s-%lx-%lx-%x", tmp_file_prefix,current_pid,
             (ulong) thd->thread_id, thd->tmp_table++);
   }
 
diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index a9416644835..b5c6eb05f38 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -10224,7 +10224,7 @@ do_continue:;
 
   backup_name.length= my_snprintf(backup_name_buff, sizeof(backup_name_buff),
                                   "%s2-%lx-%lx", tmp_file_prefix,
-                                    current_pid, (long) thd->thread_id);
+                                  current_pid, (long) thd->thread_id);
   if (lower_case_table_names)
     my_casedn_str(files_charset_info, backup_name_buff);
   if (mysql_rename_table(old_db_type, &alter_ctx.db, &alter_ctx.table_name,