Credit: Jemal Countess/Getty Images

He's being outnumbered!

Matt Damon and wife Luciana Barrosa are expecting another girl, Damon tells The Oscar-winning actor, who turned 40 last week, and Barrosa already have two daughters, Isabella, 4, and Gia, 2, as well as Barrosa’s daughter, Alexis, 11, from a previous relationship.

Their new baby is due next month.

"I'm thrilled," Damon told Us Sunday at the New York Film Festival's Hereafter premiere. "I can't wait to meet her."

Damon -- who quietly wed Luciana in 2005 -- has credited his kids with keeping him grounded in Hollywood.

“It's pretty easy to kind of lose your way... having kids is really helpful," he once told Parade magazine. "They kind of disabuse you of the notion of your greatness pretty quickly. There's a routine that you get into with kids that precludes you from going back to your single days. I'm probably more boring than I used to be. I go to bed earlier and I get up earlier."