Matt Damon knew that his pal George Clooney and his wife, Amal, were expecting months ago.

The star told ET Canada’s Matte Babel that he found out when they were working together last fall, and Clooney pulled him aside on set and shared the exciting news.

“I was so happy for him,’’ said Damon. “And I was like, ‘how far along is she?’ And he goes, ‘eight weeks.’ ’’

To which Damon replied, “ ‘Are you out of your mind?! Don’t tell anybody else! Don’t tell anybody else! Don’t you know the 12-week rule?’ Like of course he doesn’t. I was like, ‘just shut up, man.’ And then four weeks later, I’m like, ‘we’re good right?’ ’’

And Clooney said to Damon: “‘We’re good.’’’

Baby rumors swirled around the Clooneys until Thursday, when Julie Chen announced on “The Talk’’ that the couple is expecting twins in June.

Damon told ET Canada that he’s thrilled for his “Ocean’s Eleven’’ costar and Amal, whom he described as “a remarkable woman.’’