“Mad Men” hottie January Jones celebrates her 33rd birthday today, but it’s fans of scantily clad superheroines that will be dancing in the streets. In an interview with Hero Complex, the X-Men: First Class star confirmed that her Emma Frost wardrobe is—despite what leaked on-the-set photos may suggest—on the revealing side.

She says:

The costumes are insane. It’s a lot of very body-conscious stuff. If you look at the comic book, she’s barely dressed. She’s got quite the bod, which is very intimidating.

I’m a petite person, so I didn’t want to go into a strict workout and eating regime. I would have disappeared entirely, and she’s very busty, very voluptuous, so I didn’t want to get rid of any of my curves.

I don’t know about you, but my penis just breathed a sigh of relief.

Jones, who  beat out British babe Alice Eve for the role, is part of a cast that includes James McAvoy as Charles Xavier, Michael Fassbender as Magneto, Kevin Bacon as Sebastian Shaw, Rose Byrne as Moira, and Jennifer Lawrence as Mystique.

X-Men: First Class is an origins story directed by Mathew Vaughn (Kick Ass) for 20th Century Fox. The film will be in theaters on June 3.