Justin Timberlake just confirmed what we've known for months: that his wife Jessica Biel is pregnant and expecting the couple's first child! The now 34-year-old singer confirmed the news on Saturday, his birthday, by posting a photo of him kissing Biel's baby bump.

"Thank you EVERYONE for the Bday wishes! This year, I'm getting the GREATEST GIFT EVER. CAN'T WAIT," he captioned the photo. "#BoyOrGirl #YouNeverKnow #WeDon'tEvenKnow #WeAreTakingBets."

It's been rumored that the couple is expecting a baby girl due this spring. A source previously told Life & Style magazine that the parents-to-be "couldn't be more proud" and Biel is "getting everything set for their little princess."

The source added that Timberlake and Biel have both been busy decorating the baby's nursery and have opted for a jungle theme.

"They don't want frills or anything too feminine, so they commissioned an artist to paint the walls with wild animals like elephants, zebras and monkeys," the source said.

Apparently, the "SexyBack" singer is hoping the child is just as musically inclined as he is and plans on buying the baby a "drum set and a guitar."

Biel's pregnancy comes at a perfect (and busy) time for the former "7th Heaven" actress. This spring, around the time her baby is due, Biel will also be opening her kid-friendly restaurant Au Fudge. There was a small setback recently when Biel's chef, Vic Casanova, quit. At the time, a rep for Casanova told People magazine that "there are no hard feelings" but it was the best decision for the chef.

"They've run into the usual snags and delays any new restaurant owner has, but it looks like they're on track now," a source told People.

Timberlake and Biel have been married since 2012 and celebrated their second wedding anniversary in October.