While Blue Bloods fans are still mourning the cancellation of the beloved show, they had something special to celebrate on Aug. 17, as cast member Donnie Wahlberg turned 55.

Bridget Moynahan, who plays Erin Reagan, paid tribute to her on-screen brother with a sweet, personal photo as she marked the special occasion—and fans couldn’t get enough.

In the Instagram photo, Moynahan let out a natural laugh while Wahlberg looked on with a smile.

“This is @donniewahlberg convincing me I needed another Leo in my life. He wasn’t wrong. Can’t imagine my life without my brother from another mother. Love you! Happy Birthday!” she wrote in the caption.

Wahlberg replied to the birthday post, writing, “Oh Breezy! Same! Same! Same! Thankful for you, every single day! ps – Everyone needs more Leo’s in their life! 🦁♌️👑😂😎❤️.”

His sister, Tracey, also commented on Moynahan’s update with a kind message, saying, “You are so sweet❤️ he is the kindest human I know so blessed he is my brother from the same mother😘.”

Many fans wished him a happy birthday, while others shared their love for Moynahan and Wahlberg’s close relationship, like one who wrote, “Such a beautiful picture you are a brother and sister you spent many years together!”

“My heart is full! Love seeing you guys laugh and support each other! ❤️thank you for sharing,” said another, while a third commented, “Nice and reassuring to have a true friend. Congratulations 😉.”

Moynahan and Wahlberg worked on a failed pilot before they snagged the roles of siblings Erin and Danny Reagan on Blue Bloods. According to Wahlberg, as he said on The Drew Barrymore Show,  “We knew the moment we met we were gonna be friends forever.”

Although the first show didn’t make it to air, Wahlberg helped Moynahan get the role on Blue Bloods, and the rest is history.