"Happy birthday to my gorgeous baby sister, Kendall! I love you soooooo much!!! I can't believe you are 17! Xo," the E! star posted along with an adorable photo collage of her Kendall through the years.
We know our fave model-actress-tween is probably hearing this a lot today, but happy birthday!
(Sidenote: Is it possible to be envious of a person's Instagram? Because that's how we feel about seeing her smooching that koala right now!)
