Sarah Michelle Gellar and Freddie Prinze Jr. celebrated their 20th wedding anniversary Thursday, and the actress took the opportunity to call out Howard Stern for a bet he made a couple of decades ago when her husband guested on "The Howard Stern Show" in 2001, before the wedding.

On her Instagram page, Gellar posted a sweet snap of Prinze Jr. kissing her hand in an old photo from their wedding ceremony. Gellar, 45, simply captioned the photo, "20."

The actress uploaded another photo of the couple posing at sunset on her Instagram Story, and followed it up with screenshots from the 2001 interview of Stern questioning her husband about their marriage lasting, and wrote, "@Sternshow, what do you think?"

"So, you will marry Sarah Michelle Gellar even though you know it won't last?" Stern asked Prinze Jr., to which he promptly responded with a smile, "Oh, absolutely it will last."

Stern continued to grill the "Scooby Doo" actor and said, "Who do you know has a successful marriage in Hollywood?"

He continued, "I wanna make a written bet with you. In about 10 years you're gonna hunt me down and go, 'Howard, I owe you money...put your money where your mouth is. A million dollars."

Prinze earlier revealed that he and the "Buffy The Vampire Slayer" actress developed a romantic relationship while filming "I Know What You Did Last Summer" in 1997.

"We just would talk about life and stuff like that, and we had completely different philosophies on just about everything. 'Cause she was a born and raised New Yorker and I was a born and raised L.A. kid, and we just looked at everything like night and day," he told Us Weekly in 2020.

Gellar also earlier opened up about making an effort to have a successful marriage.

"You have to call and check in and dedicate that time, and most people aren't willing to put that work in. So, to have a successful relationship, whether it's marriage, whether it's friendship, whether it's business, you have to put [in] the time if you want to see the results," she said.

The couple exchanged vows in September 2002 and have two kids together.

Sarah Michelle Gellar
Sarah Michelle Gellar is happy to have inspired fans with her role in “Buffy the Vampire Slayer.” Pictured: Gellar sits down for an interview with E! News on Jan. 23, 2017 in Los Angeles. Reuters/Stringer