Contest for all-marshmallow Lucky Charms

UNDATED (CNN) — Lucky Charms cereal is going all-marshmallow, but you have to win a contest in order to get your hands on it.

General Mills says it will produce just 10 boxes of the all-marshmallow Lucky Charms.

If you want a box, you have to post a photo of yourself to Facebook, Twitter, or Instagram with an “imaginary” box of Lucky Charms, and you have to use the hashtag “Lucky 10 Sweepstakes.”

The contest runs until Sunday.