Prefix trouble in request

Message:
Table "db.users" doesn't exist query: SELECT COUNT(DISTINCT u.uid) FROM users u LEFT JOIN users_roles ur ON u.uid = ur.uid WHERE u.uid != 0 in /homepages/htdocs/includes/database.mysqli.inc on line 151

Patch:

File: user.module
2030c2030
< $query_count = 'SELECT COUNT(DISTINCT u.uid) FROM users u LEFT JOIN users_roles ur ON u.uid = ur.uid '. $filter['join'] .' WHERE u.uid != 0 '. $filter['where'];
---
> $query_count = 'SELECT COUNT(DISTINCT u.uid) FROM {users} u LEFT JOIN {users_roles} ur ON u.uid = ur.uid '. $filter['join'] .' WHERE u.uid != 0 '. $filter['where'];