Problem using REPLACE() in mysql

Hi,
this is is my select

PHP Code:

$builder = $this->db->table('table_name')->select('id,REPLACE(price,'.',',') AS my_price');
echo $builder->getCompiledSelect(); 


The result is:

Code:

SELECT `table_name`.`id`, REPLACE(table_name.price, '.', ', ') AS my_price FROM `table_name`

there is a space after the comma (', ') of replace. Is it a bug? how can I solve it?