Bindi Irwin is making sure her brother Robert Irwin's 17th birthday is extra special.
The proud big sister posted a heartfelt birthday tribute to her brother, who was born Dec. 1, 2003. While American fans are seeing the post on Monday, it's already Tuesday in Australia, which means it's the younger Irwin's birthday.
"Happy Birthday to my amazing brother! Your kind heart and fantastic sense of humour makes my every day," Bindi Irwin wrote in the Instagram tribute.
The siblings, who are the children of the late "Crocodile Hunter" Steve Irwin, have a close bond. Along with the birthday message, Bindi shared a photo of Robert walking her down the aisle on her wedding day and another photo of them embracing on the big day.
Bindi Irwin married her longtime love Chandler Powell in March in an intimate ceremony held at the Australia Zoo. The couple announced in August that they're expecting their first child. In September, they shared the news that they'll be welcoming a daughter in early 2021.
"Our baby girl is going to love her ‘funcle’ (fun uncle) so very much," Irwin wrote in the birthday post. "You’re one of the brightest lights the world has ever seen. I’ll always be here for you. Love you!"
It's not the first time Irwin has gushed about her little brother. In October, she penned a sweet note to the teenager on Instagram, letting him know what an awesome uncle he's going to be.
"Shoutout to my little brother (who definitely isn’t ‘little’ anymore) for being such an incredible friend," she wrote. "You’re always there for me and I know you will be the best uncle when our baby girl is born."
Irwin has been keeping fans updated throughout her pregnancy. Last week, she shared an ultrasound video of her baby girl, adding that she is "beyond thankful."