The Law & Order: SVU stars have maintained a close friendship for more than two decades

Mariska Hargitay is sending birthday wishes to Christopher Meloni!

On Sunday, the actress, 58, shared a sweet tribute to her longtime friend and costar in celebration of his 61st birthday. “Happy 61 @Chris_Meloni you’re aging like a fine wine cheers,” Hargitay captioned the Instagram photo, adding the hashtag #HeStillGotIt.

In the shot, Hargitay and Meloni are seen sharing an embrace with the actor’s back turned to the camera. Making the moment all the more celebratory, Meloni sported a glittering jacket with the numbers “21” and “61” across the back.

After more than two decades, the friendship between the Law & Order: SVU stars is still going strong.

Law & Order: SVU premiered on NBC in September 1999 and has been on the air for 23 seasons, becoming the longest-running primetime live-action series in the history of U.S. television.

Mariska Hargitay and Chris Meloni

DIMITRIOS KAMBOURIS/GETTY

On the show, Meloni played Elliot Stabler while Hargitay portrays Olivia Benson. The pair starred as partners for the first 12 seasons of SVU until Meloni departed in 2011.

Meloni has since returned to the franchise and is starring in his own spin-off series, Law & Order: Organized Crime.

During an appearance on Late Night with Seth Meyers last week, the actors opened up about their unique chemistry.

christopher meloni and mariska hargitay

NATHAN CONGLETON/NBC

“You never think that, after being a struggling actor for so long, that any show’s gonna go,” Hargitay explained. “But this was a unique audition for us because when we met, there was a certain chemistry, so I actually wasn’t nervous at the audition.”

“But you never think what happened [with the show’s fame] would happen,” she added. “You can’t dream it!”

Since reuniting last year, SVU fans have continued to hold out hope that Elliot and Olivia’s friendship will eventually turn romantic, thanks in part to Meloni and Hargitay’s social media trolling.

In a recent interview with PEOPLE, Hargitay said the show is “taking it one step at a time” in regards to Olivia’s evolving relationship with Elliot.

“It’s such a complicated relationship that I think we just want to respect the complexity and the nuance of it,” she explained. “He’s in a new job and he’s sort of unbalanced … But what we do know is that Olivia loves him, will always love him, will always be there and they have a bond like no other.”

Added Meloni of a potential relationship with Olivia: “In the future, I don’t not see it. That might be very satisfying for a lot of people, I’ll leave it at that.”