jarodtaylor on "Anyway to show "current-cat" class on the show_option_all"

So I have a list of categories using wp_list_categories. I'm using the show_option_all param so that the list is built like so:

<ul class="product-categories">
    <li><a href="#">All Categories</a></li>
    <li class="cat-item cat-item-1"><a href="#">Category One</a></li>
    <li class="cat-item cat-item-2"><a href="#">Category Two</a></li>
</ul>

When I click on any of the categories the <li> gets a class of "current-cat". Unfortunately if I click on "All Categories" I do not get that class.

Is this a simple param or will I need to do something custom?

Thanks!