laravel 5.1 + phpdesktop gives fatal error: Call to undefined function mb_internal_encoding()

I am trying to use Laravel 5.1 with phpdesktop (http://ift.tt/QkNs6i). I configured everything according to instructions but I get a fatal error for the first page itself.

Fatal error: Call to undefined function Illuminate\Foundation\Bootstrap\mb_internal_encoding() in H:\app\laravel\www\vendor\laravel\framework\src\Illuminate\Foundation\Bootstrap\LoadConfiguration.php on line 43

I am unable to solve this problem. Both PHPDesktop and laravel versions are latest ones.

via Chebli Mohamed