Mariah Carey sang her modern Christmas classic 'All I Want for Christmas Is You' at the National Christmas Tree Lighting event in Washington, D.C. last week. Her voice cracked throughout the performance, and she sounded like she was sick. It was really bad, which is shocking for Mimi.

For the top half of the performance, Carey sounded winded -- and she missed more than a few notes. But it was cold and she was outside, so we'll cut her some slack there.

Besides, the diva looked amazing in her clingy white dress, showing off her curves, which appeared toned. But make no mistake -- her voice was O-F-F!

We know that Mimi would get flack if she lip-synced, and now she is going to get it for how her voice sounded. #PopStarProblems. We must say that it was not her best performance, and we love this song. But Mimi was clearly struggling.

Fast-forward to 3:28 and you will hear her voice crack horribly and sound awful from that moment through the end of the song.

Memo to one of her assistants: Get her some tea and honey, stat! Lambs (and we) still love her, though!