Matt Damon 'almost cried' when George Clooney told him about Amal Clooney's pregnancy

Matt Damon revealed on Thursday how his longtime friend, George Clooney, told him that he and his wife, Amal, were expecting twins -- and it was a while ago!

Speaking with ET Canada just hours after the exciting news broke, "The Great Wall" star couldn't contain his excitement for the couple and was clearly relieved to be able to speak openly about the secret he's known since Amal was just eight weeks pregnant.

SEE ALSO: Amal Clooney is pregnant with twins, George Clooney to become a dad in June!

"I was working with him last fall and he pulled me aside on set and, I mean, I almost started crying," he said with a smile. "I was so happy for him, and I was like, 'How far along is she?' And he goes, 'Eight weeks.'"

See photos of Matt Damon:

"'Are you out of your mind?! Don't tell anybody else! Don't tell anybody else! Don't you know the 12-week rule?,'" he replied to Clooney at the time. "Like, of course he doesn't. [...] And four weeks later, I'm like, 'We're good, right?' 'We're good.'"

The news comes after months of speculation around Amal, who had been stepping our in lose-fitting clothing for weeks, but clearly the couple wanted to wait until they were ready for the world to know their news. Neither Amal nor George have children yet, so their twins -- who are expected to arrive in June! -- will be their first kids.

"I'm thrilled for him," Damon finished. "She's amazing. He hit the jackpot, just on every level. She is a remarkable woman. They're gonna be great. They're gonna be awesome parents. Those kids are lucky."

Watch Matt Damon's full interview with Entertainment Tonight Canada in the video above.

See photos from the Clooneys' star-studded 2014 wedding:

More from AOL.com:
Rosie O'Donnell as Steve Bannon: Jaw-dropping photo emerges on Twitter
Martha Stewart has a snowplowing snafu, gets stuck: See the pic!
Debra Messing recalls 'Walk in the Clouds' director pressuring her to do naked sex scene, mocking her nose