Baby on way for 'Always Sunny' stars

People mag reports that Philly bred Rob McElhenney and his Always Sunny in Philadelphia costar and wife Kaitlin Olson are expecting a baby in August.

The couple -- she's 34 and he's 32 -- were married in September 2008.

It's not clear how Olson's pregnancy will affect production of the show, which had been scheduled to visit Philly in June to shoot exteriors.

The couple are investors in Mac's Tavern, a bar opening in the next five weeks in Old City.