Adding menu badge causes navigation menu to render incorrectly

When I add menu badges to the private messages nav bar item, it causes the nav bar to render incorrectly.

Here's how it looks without the badge (how it should render):

http://drive.google.com/uc?export=view&id=0B7PIeljVlHLeWEhGMUVpb0dnNDQ

And here's with a badge:

http://drive.google.com/uc?export=view&id=0B7PIeljVlHLecXZUV0R0UEZ2X0U

Notice the bottom line has disappeared.

Any help would be most appreciated!