Last month, Michael Douglas was beaming with pride for his daughter Carys at her high school graduation.

But the 76-year-old father did have an awkward moment at the ceremony, when fellow parents mistook him for the grandfather of his 18-year-old daughter.

Michael Douglas mistaken for daughter Carys' grandfather

On The Kelly Clarkson Show this week, Douglas opened up about the awkward mix-up. "It's a little rough," he said of the confusion at his daughter's graduation.

Douglas was exchanging congratulations with other parents, when they told him: "You must be so proud of your granddaughter."

"I'm not going to take it personal," Douglas laughed. "I know they're just trying to be nice," he added, now wearing white hair and a grey beard at age 76.

Despite the mix-up, Douglas said the family had a "lovely experience" at the virtual ceremony, adding that he and his wife are "so proud" of their daughter.

Michael Douglas, Catherine Zeta-Jones celebrate their family

Last month, both Douglas and his wife Catherine Zeta-Jones paid tribute to Carys after her milestone. Here's the great photo they shared from the special event.

As Douglas said, it's perhaps an understandable mix-up. In his second marriage, to Zeta-Jones, he welcomed two children — Dylan in 2000 and Carys in 2003 — over 20 years after he first had his son Cameron in 1978.

Douglas was married to Diandra Luker until 2000, when he also married Zeta-Jones and started a family with her. You can learn more about the children of Michael Douglas here.