Add custom class

Hi!
I’m trying to add a custom class to my custom author widget, but when I pass the argument to the get_avatar function it just doesn’t show up in my page, if I deactivate this plugin it works fine.
Is there a custom function I can use to retrieve my avatar with a custom class using this plugin?
my code looks like:

<div class=\"author-box__gravatar\">	
		".get_avatar(get_the_author_meta('ID'), 100, '','', array('class' => array('my-class1', 'my-class2')) )."
		</div>