Robert Downey Jr. has expressed interest in reprising his role as Iron Man in the Marvel Cinematic Universe. Which presents a problem, since he died at the end of Avengers: Endgame.

Speaking with GamesRadar at the Sands: International Film Festival, the film’s directors, Joe and Anthony Russo, seemed baffled at the notion of a Downey return.

“I don’t know how they would do it,” Anthony Russo told GamesRadar. “I don’t know what the road to that would be.”

“I mean, we closed that book, so it would be up to them to figure out how to reopen it,” Joe Russo added.

Marvel head Kevin Feige refuted the claim it was mulling over bringing Iron Man back. Speaking with Vanity Fair, Feige said Marvel Studios could not “magically undo” Tony Stark’s death in Avengers: Endgame.

“We are going to keep that moment and not touch that moment again,” Feige told Vanity Fair. “We all worked very hard for many years to get to that, and we would never want to magically undo it in any way.”