The 1989 hitmaker wished her brother Austin a happy 24th birthday with the most adorable throwback photo of the Swift siblings.
"HAPPY BIRTHDAY AUSTIN!!!!! Thanks for 24 years of LOLs," Swift, 26, wrote on Instagram and Twitter Friday.
Along with her caption, Taylor shared a snap of the pair LOL-ing for a cute brother-sister portrait. The 10-time Grammy winner sported a colorful print dress along with natural blonde curls while little Austin wore a blue collared shirt and khakis.
Over the years, the University of Notre Dame alum has been very supportive of his famous big sister.
Not only did he have Taylor's back during the latest Kanye West feud, he's also close with the other important man in Taylor's life, her boyfriend of one year Calvin Harris.
Also, Austin is a great red carpet date. He's joined his pop star sister on many award shows and A-list events most recently, the Vanity Fair Oscars after-party.