$this->uri->uri_to_assoc() Replaces Period "." (dot) With An Underscore "_"

[eluser]morehawes[/eluser]
Hi all, this has got me truely stumped so I am wondering if anyone has any ideas! Getting URI data using uri_to_assoc is replacing "." (period) with "_" (underscore). For example this basic controller :

Code:

<?php class Test extends Controller {
    function get_data() {
        echo '<pre>';
        print_r($this->uri->uri_to_assoc());
        echo '</pre>';
    }
}

When given the URL "http://www.myurl.com/test/get_data/usern...hawes.test" outputs this :

Code:

Array
(
    [username] => morehawes_test
)

I have also checked my config to ensure periods are allowed :

Code:

$config['permitted_uri_chars'] = 'a-z 0-9~%.:_\-';

I would really really appreciate it if anyone could help with this

Many thanks!