The upcoming Wicked musical movie doesn’t use canned vocals, director Jon M. Chu says.

Both Cynthia Erivo and Ariana Grande insisted on singing live during the production of his big-screen adaptation of the stage show. Their vocals will be used in the finished version of the film.

“These are live vocals,” Chu told Vanity Fair. “When we were shooting it, those girls were like, ‘F— the pre-records. We’re going live.’”

Chu was hesitant, telling his stars that there would be “a lot of wind” in their air pipes while performing and singing at the same time. But Grande and Erivo persisted, telling the filmmaker, “‘Yeah. That’s what we do.’”

Grande has long sought to be in a film version of the Broadway musical. She admitted to “stalking” the audition process, which Chu noticed.

“It was literally 10 years of being like, ‘Knock, knock, any developments? Is there an audition coming this year, or next year? I would like to start preparing today.’” Grande said.

Chu said that she’d “be there at least 30 minutes early” across the audition cycle.

“I’d see her car circling. I’d be like, ‘Who is that?’’” Chu said. “‘That’s Ariana Grande.’ ‘Why is she here so early?’”

The first of Chu’s two Wicked movies arrives Nov. 27 in theaters.