Kim Kardashian didn’t let the day end before wishing her firstborn nephew Mason Disick a happy 13th birthday.

The mom-of-four took to Instagram Stories to upload a photo of the two standing back to back, proving that Mason had surpassed Kim’s 5foot2inch frame.

She wrote over the image, ‘The day has come where you’re taller [than] me now.’

In the photo the proud aunt was dressed in a gray jacquard Skims robe with black sunglasses and a black backpack on her shoulders.

Mason wore a backpack as well, along with gray sweatpants and a white t-shirt as he carried a sweatshirt.

The entrepreneur was seen with the platinum blonde locks she’s rocked throughout the year and the youngster sported a shaggy mushroom haircut.

Kim added in the post, ‘I just love who you are and I’m just so proud of you Mason. Welcome to your teenage years. Happy Birthday.’

Flashback: Kim and Mason pictured together in a throwback photo

Kourtney Kardashian and Scott Disick’s second son Reign shares a birthday with his older brother.

The boys were both born on December 13 but are five years apart, and Reign is now eight-years-old.

Their sibling, sister Penelope Scotland Disick, turned ten-years-old in July.

Oh boy: Kourtney Kardashian and Scott Disick’s two sons had birthdays on Wednesday. Seen with Mason who is now 13

The POOSH founder’s family was quick to take to Instagram to wish the boys well.

Momager Kris Jenner — who the children call Lovey — was the first to post.

‘Happy birthday to two of the brightest lights in my life, my beautiful grandsons, Mason and Reign!’ she wrote in her caption as she shared several throwback photos.

‘Mason, you are my first-born grandson, and I am so very proud of you each and every day! 

Thanks Kris: The boys were both born on December 13 but are five years apart

Her second son: Kourtney is seen with Reign who has turned eight years old

‘You’ve grown into such an amazing young man, and I adore you.’

She then turned her attention to the younger boy.

‘Reign, you are the funniest!!!! You are one special guy with so many facets to your personality!!!’ she noted.

‘Both of you have the most amazing qualities and are kind, considerate, loving, so smart, so talented in so many ways, and such a special magical part of our family … 

‘AND it’s wild that you were born on the very same day!!!! Five years apart!!!!

‘You are both the best sons, grandsons, brothers, nephews, and friends to all of us and I love you so much!!!!!!! Lovey xoxo.’

Little one: The POOSH founder’s family was quick to take to Instagram to wish the boys well

The note: Momager Kris Jenner – who goes by Lovey to the kids and not grandma – was the first to post. ‘Happy birthday to two of the brightest lights in my life, my beautiful grandsons, Mason and Reign!’

This comes after Kourtney said she is finally getting her energy back ten months after stopping IVF treatment.

The reality TV star had been trying to grow her family by having a baby with new husband Travis Barker, and they embarked on a gruelling regime of fertility treatments in an effort to get pregnant.

They stopped earlier this year and now she says she’s feeling like herself again.

In a post on Instagram, the mom-of-three wrote: ‘Finally started getting my energy back 10 months after stopping IVF. For anyone else going through it, it gets better!’

She shared the message alongside a picture of herself on a treadmill — suggesting she feels up to exercising again. 

In her arms: She wrote in her caption as she shared several throwback photos. ‘Mason, you are my first-born grandson, and I am so very proud of you each and every day!’