Brad Pitt turns 54 on 18 December. And, to celebrate his big day his six children are reportedly planning a big surprise that will sweep him off his feet.

How is the Jolie-Pitt brood planning on celebrating their dad's birthday?

According to Hollywood Life, Maddox (16) and Pax (13) are planning on cooking a "special birthday dinner", while his daughters — Zahara (12), Shiloh (11) and Vivienne (9) — are going to treat their dad with a birthday cake. Knox, who is 9 years old, will also be by his father's side when they celebrate the occasion.

Pitt is said to be "looking forward to his birthday this year as he's going to have all the kids with him", a source told the celebrity gossip website.

Pitt reportedly has been feeling much better after a rough twelve months following his separation from Jolie. He has also been seeing the children more often as they now live close by.

"Brad's children mean everything to him, and he hates not being there every day with them, but he's seeing a lot more of the kids now that they're living close by, and he feels like he's finally able to make up for lost time," the source said.

The person added, "Brad was feeling really down on his birthday last year, but he's now back on track and has started really looking forward to the future again."

This comes just days after it was said that Pitt is worried about having a "Blue Christmas", with the actor reportedly thinking that his former wife Angelina Jolie might take their six children overseas during the holidays.

"The holidays are extra hard for Brad," a source previously told Hollywood Life. "He misses his kids more than ever. He does get to see them but it's not nearly as much as he would like and it's always up to Angelina when it happens."

Pitt and Jolie split in September 2016 after two years of marriage. They first met each other while filming the 2005 movie Mr & Mrs Smith.