__DIR__ throws errors

Activated the plugin and navigated to Tools > Post Type Icons and found the following errors that prevented the page from loading:

Notice: Use of undefined constant __DIR__ – assumed ‘__DIR__’ in [my website]/wp-content/plugins/post-type-icons/post-type-icons.php on line 66

Warning: require_once(__DIR__/font-awesome/class-pti-font-awesome.php) [function.require-once]: failed to open stream: No such file or directory in [my website]/wp-content/plugins/post-type-icons/post-type-icons.php on line 66

Fatal error: require_once() [function.require]: Failed opening required ‘__DIR__/font-awesome/class-pti-font-awesome.php’ (include_path=’.:/Applications/MAMP/bin/php/php5.2.17/lib/php’) in [my website]/wp-content/plugins/post-type-icons/post-type-icons.php on line 66

-PaulMighty

http://wordpress.org/plugins/post-type-icons/