Hilary Duff's little boy is growing up so fast!
The former Disney Channel star shared a sweet birthday message for her son Luca -- who turns five on Monday -- to Instagram over the weekend, ringing in the big milestone with lots of love.
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"Hey kid.... the past 5 years have been the BEST, hardest, most blessed years of my life," the 29-year-old actress wrote. "I love you so much. The world is yours my love ...I hope you take it❤️Happy Birthday Luca Cruz."
Duff also shared a cute photo of Luca rocking some serious attitude in adults sunglasses, jokingly captioning the pic, "Teenagers.."
WATCH: Hilary Duff: 'I Feel Like I Was Judged for Having a Baby Too Soon'
Happy birthday, Luca!
Meanwhile, Duff recently opened up about her divorce from Mike Comrie last year, after six years of marriage.
Watch the video below for more.