Adding Link to an Entire Button & Not Just to the Button's Text

I'm using a button in an email, and when I add a URL link, just the text on the button becomes a clickable link. The entire button itself is not a clickable link. So, if a recipient clicks on the colored part of the button, there's no link. If they hover directly over the button's text, there's a link. Anyone know how to make the entire button a clickable link?