Subdirectory install missing slash in blog-path

Hey guys,

I installed WHMCS, WordPress Multisite and the Provisioning Plugin. Everything works fine except for a small, but important detail: The plugin creates the blogs without a leading slash, e.g. the multisite-URL is "wpmu.com", the selected domain "dev", the new blog created would have the URL "http://wpmu.comdev/" instead of "http://wpmu.com/dev/".

In the network admin's site edit screen the domain field says: "http://wpmu.com"; the path-field: "dev/".

I could fix this by changing line 318 in the plugin's file whmcs-mrp.php from
$path = $base . $domain . '/';
to
$path = $base . '/' . $domain . '/';

Could this bug be caused by my setup? I'd prefer to leave the plugin-code untouched for future updates.

Thanks.
Manuel