PHP Warning

I get the following PHP warning in my error log each time somebody logs in:

[25-Oct-2012 13:53:46 UTC] PHP Warning: Illegal string offset 'login_redirect' in .../public_html/wp-content/plugins/login-with-ajax/login-with-ajax.php on line 300

I am using PHP 5.4. It still works fine, but it would be nice if this were fixed in future.

Thanks.

http://ww.wp.xz.cn/extend/plugins/login-with-ajax/