Happy birthday, Nori! Kim Kardashian kicked off North West's 3rd birthday celebration by posting an adorable Instagram video of the two on Wednesday, June 15.

"She promised me she wouldn't get any bigger," Kardashian, 35, captioned the post. "I can't believe my baby girl is 3 years old today!!!! Northie I love you so much I can't even explain it! Happy Birthday to my favorite mermaid!!!"

In the clip, Kardashian and Kanye West's daughter is beaming while being held by her famous mom. "You are not going to get any bigger. You are not going to get any taller and you are going to stay little forever. OK?" Kardashian asks.

North smiles and replies: "OK!"

The Keeping Up With the Kardashians star and West, 39, who are also parents to 6-month-old son Saint, usually go big for North's birthday. Last year, the family had a Minnie Mouse–themed party at Disneyland in Anaheim, California. The family closed off the Big Thunder Ranch Jamboree in Frontierland and mingled with Elsa, Anna, Olaf and other Frozen characters.

"Anna and Elsa made an appearance because North loves them and she's a Frozen fanatic," a source told Us at the time. (In March 2015, Khloé Kardashian posted a video of North holding on to a Frozen rolling suitcase at an airport.)

North's 1st birthday festivities were just as lavish. In 2014, Kimye threw her a "Kidchella" in Kourtney Kardashian's backyard in Calabasas, California. The Coachella-inspired party included a Ferris wheel, an inflatable slide, face paint and white tents.

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