How can I add a CSS class to Sociable links

I’d like to add class="snap_nopreview" to my Sociable links.

I thought I might be able to add the class to Line 797 of sociable.php, as such:

$html .= "\n<div class=\"sociable\" \"snap_nopreview\">\n";

However, that didn’t work.

The extra class is necessary to disable site previews provided by my Snap script.

Any suggestions on how I might accomplish this?

Thanks.