Idris Elba first met his ‘The Dark Tower’ costar Matthew McConaughey in … the bathroom?!

The movie adaptation of The Dark Tower, Stephen King’s sci-fi Western book series, brings two superstars together: Idris Elbra and Matthew McConaughey.

But the A-listers became friendly in an … unexpected place before being cast, Elba told Entertainment Weekly Radio at Comic-Con in San Diego on Thursday.

“Matthew and I met in the men’s restroom at one of the award ceremonies. I think he’d just won an Oscar, and I was congratulating him over one of the stalls,” he said, laughing. “It was a bit awkward.”

While filming in South Africa, Elba and McConaughey, “sort of avoided each other, because the Man in Black and Roland don’t see each other,” he added. “So we played that chemistry a bit until we got onto set, and it was great. It really worked for the story, and it worked for that particular scene.”

The Dark Tower hits theaters in February 2017. Hear the full interview with Elba on demand by searching his name on SiriusXM’s app.

Tune into SiriusXM EW Radio (Ch. 105) through the weekend starting at noon for more live coverage of Comic-Con.

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