Ian McKellan officiates the couple's surprise ceremony
Credit: Larry Busacca/Getty

Sir Patrick Stewart has embarked upon a new Enterprise: marriage!

Stewart married his longtime girlfriend, Brooklyn singer and songwriter Sunny Ozell, on Saturday afternoon, his rep confirms to PEOPLE.

The ceremony took place beside Lake Tahoe in front of 100 friends and family. The bride wore a white French lace dress by Temperley London.

“Yes, married,” the actor, best known for traveling the galaxy as Captain Jean-Luc Picard in Star Trek: The Next Generation, wrote alongside a Twitpic of himself and his new bride having a ball, their bodies submerged up to their heads in a ball pit.

And who officiated the nuptials but Sir Ian McKellan, Stewart’s friend and costar in the X-Men franchise?

“I did my part,” McKellan, 74, posted on his Facebook page, alongside a photo showing the actor sporting his “Doctor of Divinity” license and a T-shirt reading “Minister.”

Stewart, 73, and Ozell, 35, have dated since 2009, with some hints recently that a marriage might take place.

McKellan appeared to let the cat out of the bag during a March appearance on the British talk show The Jonathan Ross Show when he said, “I’m going to marry Patrick. I’m going to officiate at his wedding.”

And on Saturday Ozell Tweeted a photo of her feet, toes painted red, immersed in crystal-clear water, lake stones at the bottom.

“Don’t tell me you’re getting cold feet!!!!” one of her followers responded.

The marriage is Stewart’s third. He was previously married to Sheila Falconer, from 1966-1990, and Wendy Neuss, from 2000-2003.

Additional reporting by MONICA RIZZO