Kim Kardashian is one proud aunt.
On her web site, she posted an adorable shot of her nephew Mason, who was born last December.
"Mason is the happiest baby!" she wrote under the photo. "There are no words to describe how much I love my little Mason! Isn't he gorgeous?"
On Saturday, Mason's mommy, Kourtney Kardashian, celebrated her 31st birthday at Wet Republic in Las Vegas with her sibs.
Motherhood is "amazing," she told UsMagazine.com. "Everything that everyone says about it is true.”
Mason's latest milestone?
"He has been rolling over a lot and he laughs hysterically like everyday and it’s so cute! He is obsessed with his feet.”