It's time to start keeping up with teenage Mason Disick.
Kim Kardashian shared a snap of her nephew Mason in honor of his 13th birthday—and in honor of the fact that he is all grown up.
"The day has come where you're taller then [sic] me now," Kim wrote on her Dec. 14 Instagram Story. "I just love who you are and I'm just so proud of you Mason. Welcome to your teenage years. Happy Birthday."
Kim paired the sweet message with a photo of herself and Mason standing back to back. And yes, as seen in the snap, Mason is a little taller than the blonde-haired SKIMS founder.
As for how the teenager celebrated his special day, dad Scott Disick—who shares Mason, son Reign, 8, and daughter Penelope, 10, with ex Kourtney Kardashian—gave fans a glimpse into Mason's birthday dinner by posting a photo of party guests seated at a table at Nobu.
"Happy birthday 2 my better half," Scott wrote on his Dec. 14 IG Story. "Love you mason."
Of course, Kim and Scott weren't the only ones to shout out Mason. Kourtney took to her Instagram with a sweet throwback photo of Mason and Reign to honor both of their birthdays—which fall on the same day.
"December 14th… one of the best days of my life," Kourtney wrote Dec. 14. "Twice and forever. my birthday boys."
Users took to the comment section under Kourtney's post to show her sons some love, including family friend Malika Haqq, who wrote, "Happy birthday to your babies."
In the blink of an eye, at least one of Kourtney's babies doesn't seem to be a baby anymore!