Cindy Crawford's son honored his sister with a new tattoo Thursday.

Presley Gerber, 18, paid tribute to sibling Kaia Gerber by getting the 16-year-old model's name and the roman numeral for "23" inked on his left arm.

Presley, who visited celebrity tattoo artist JonBoy at Big Bang Tattoos in New York, showed off his tattoo on Instagram.

"23," he captioned a photo of his ink.

Kaia shared the same picture in a post on Instagram Stories.

"@presleygerber best big bro ever," she gushed. "@jonboytattoo."

Presley and Kaia's parents, supermodel Cindy Crawford and entrepreneur Rande Gerber, voiced their approval in the comments of Presley's post.

"Cool," Cindy remarked.

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"RG + JG APPROVED!" Rande wrote.

Presley is an aspiring model and photographer, while Kaia has modeled for such brands as Prada, Versace and Chanel.

Kaia told People in May that she's had several opportunities to work with her brother.

"I love working with him and every time we book a job together I get excited," the model said.

"At first when we were starting out, we used to shoot a lot together and we would just be there for each other, which is important, especially just starting in such a scary industry -- to have someone there that you're comfortable with," she added.