Kourtney Kardashian is celebrating her babies.
The Poosh founder posted a sweet birthday tribute to sons Mason, 13, and Reign, 8, who have the same birthday, a snap of the brothers hugging while wearing matching gray pajamas.
"December 14th… one of the best days of my life," Kourtney wrote in a Dec. 14 post alongside the throwback pic. "Twice and forever. my birthday boys."
The Kardashians star's post was met with love from friends and family, with many taking to the comments to wish the two boys a happy birthday.
Sarah Howard wrote, "Happy birthday and happy birthing day to you," while the Kardashian's longtime friend Malika said, "Happy birthday to your babies."
Kim Kardashian also marked the occasion by writing a sweet note of her own to Mason on her Instagram Stories.
"The day has come where you're taller then [sic] me now, " the Skims founder wrote next to a pic of her standing bedsides Mason. "I just love who you are and I'm just so proud of you Mason. Welcome to your teenage years. Happy Birthday."
Earlier this year, Kourtney and Scott Disick—who also share daughter Penelope, 10—celebrated another of Mason's milestones: finishing the sixth grade.
Kourtney celebrated her son's accomplishment with a congratulatory Instagram Stories post that included a balloon display that spelled out, "Yay Mason passed the 6th grade."
"Congrats Mason you passed the 6th grade," Scott wrote alongside the photo on June 1, "let's party."
As for Reign, well, Kourtney recently admitted she's still holding on to her little one in a unique way: with a lock of hair.
"I have Reign's hair, because we didn't cut his hair until he was five," Kourtney said in an Interview Magazine piece in November. "So I have his long braid and I smell it often."