Rated 5 out of 5 stars

Some websites have microscopic text when viewed on a phone, because the site's designer just doesn't bother to support mobile users - an addon like this is an absolute necessity, if the browser itself doesn't allow you to set a minimum font size. Wish this were compatible with Firefox 39.

This review is for a previous version of the add-on (4.3). 

It is compatible with the latest versions on desktop. It just hasn't been ported to Firefox mobile (nor will it be, unless someone donates $5000).