Kourtney Kardashian has revealed her third child will be a boy.

The pregnant reality star and her longtime partner Scott Disick are already the parents of 5-year-old son Mason and 2-year-old daughter Penelope. Their new baby is due to be born this holiday season.

Kardashian announced the baby's gender on Sunday's edition of "Kourtney & Khloe Take the Hamptons" on E!

"Mason ran in here with the blue stick. There was a red star or a blue star," Kardashian explained before sharing a home video of the moment captured by her sister Kim.

"I wanted a girl," Mason said.

His Aunt Khloe then said: "Girls don't like aliens and Lego guys. When you have a brother, you can say, 'Look at all my Lego guys, brother.' You get to be rough and you can boss him around because you're the older one."