While changing the code for my +1 button to use the recently announced +Snippets, I noticed that the +1 Button Generator is outputting invalid syntax when using HTML5 and specifying a URL.

The generator currently outputs something like:

<div class="g-plusone" data-annotation="inline" href="http://foo.com"></div>

When the correct syntax should be:

<div class="g-plusone" data-annotation="inline" data-href="http://foo.com"></div>

Took me a while to figure out what was going on.

I've reported the problem on the Webmaster Central forum.