Will Ferrell is to become a father for the third time.

The 'Step Brothers' star — who already has two sons, five-year-old Magnus and two-year-old Mattias — and his wife Viveca Paulin are expecting another boy.

A source said: "They are thrilled and can't wait to meet the latest addition to their family. Both boys are excited about being big brothers."

Viveca is due to give birth in January.

Despite being known for his comedy skills, Will recently admitted his sons haven't inherited his humorous gene.

He said: "No, they're not funny. They're deadly serious."

As an experienced parent, Will has previously given out advice to his celebrity friends. When his 'Bewitched' co-star Nicole Kidman gave birth to daughter Sunday Rose last July, he jokingly advised her to talk to her newborn daughter "at least once a week".

He said: "For me, I would advise to talk to your children, at least once a week. If you've got time, do it two or three times a week. But otherwise, I find the times where I let weeks and weeks go by without talking to my children, that adds up."