Actors Kaitlin Olson and Rob McElhenney Announce Second Pregnancy 29336

Kaitlin Olson and Rob McElhenney, co-stars of the FX sitcom It's Always Sunny in Philadelphia, have announced that they are expecting their second child this spring, reports.

The baby, a boy, will join 13-month-old big brother Axel Lee.  The couple married in 2008.

"We're having a boy! We're so happy that Axel gets to have a brother so close in age. And that I get to add another set of balls to my very, very male world," the actress, 36, joked to PEOPLE.

For more celebrity pregnancy news, check out's 2011 Celebrity BumpWatch.