Change config path?

I added a site.php in the root of my site with this:

$kirby = kirby();
$kirby->roots->config = kirby()->roots()->index() . DS . 'config';

I also tried echo just to see that it runs and that the root is correct and it is. Still it uses the old config path. Did I miss something?

I have a new config file in:

Aghh, I’m so stupid today. I was using Kirby 2.3.2. Case solved!