Duff and Comrie unite to celebrate son Luca's birthday. Credit: Courtesy Hilary Duff via Instagram

Putting their differences aside. Hilary Duff and Mike Comrie proved that divorce does not have to affect the kids when they reunited to make sure their son, Luca, got the 4th birthday celebrations he deserved.

Sharing an adorable picture of the once-married mom and dad posing with their little boy on his 4th birthday, Duff and Comrie showed that nothing's as important to them as the happiness of their kid.

"We are so proud of this boy," a happy Duff, 28, captioned the photograph which showed her tickling her son around his waist while dad Comrie, 35, carries him on his hip.

In another snap shared via Snapchat earlier in the day, the former couple were shown celebrating together at Duff's mom's house.

Keeping it together for the kids has become somewhat of a family tradition for Duff and Comrie, who are following the latest celebrity trend for amazingly amicable splits.

The Younger star recently revealed to Ellen DeGeneres that she and her former NHL star hubby manage to make it work because they're both so in awe of their little boy.

"We have such a great kid, and we're both so obsessed with him," she said. "We are good friends and we laugh a lot and we have a great communication. We share pictures when one is not with Luca. Yeah, he's great. We are great and we keep on trucking."

The duo share joint custody of their son after their divorce was finalized in January. A few days after they sorted all the details of their divorce, the ex couple went on vacation to Hawaii together.

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