Putting mirror (vanity) lights back in properly

Sorry if this has been asked before, but I couldn't find a solution on this forum or any others. I made the mistake of completing removing the lights above both the drivers side and passengers side mirrors (the ones in the sun covers), thinking that was necessary to replace the bulbs. Of course, I found out afterwards that I didn't need to do that. It seems like it should be easy to pop them back into place, but there is nothing really holding them in. There's only one tab to keep them in place and it's not enough.

Did I miss something? Is there some other piece that will keep them solidly in place or did I completely screw things up? Right now, they are "in place" but a solid bump knocks them out and they look pretty poor as they are. Any help would be gladly appreciated!