Custom Helper class is not found

I have followed this answer: http://ift.tt/23D8Ul1

My config/app.php:

'aliases' => [

    ....
    'Helper'    => App\Helpers\Helper::class,
 ],

My app/Helpers/Helper.php:

<?
namespace App\Helpers;

class Helper
{
    public static function hello($name)
    {
        return 'Hello ' . $name;
    }
}
?>

And yet, when I use in a view, I get this:

ErrorException in AliasLoader.php line 66:
Class 'App\Helpers\Helper' not found (View: [redacted]/machine/index.blade.php)

Why? This doesn't make any sense to me. I also ran composer dump-autoload and nothing changes.

via Chebli Mohamed