Ian McKellen recently appeared alongside Michael Bublé, Taron Egerton, and Carey Mulligan on The Graham Norton Show.

Norton asked McKellen about his upcoming project with Judi Dench: the new film adaptation of Andrew Lloyd Webber’s Cats. McKellen is set to play Gus the Theatre Cat; the actor even began to sing his song in the clip above.

He also revealed the strange—and at times fishy—tactics he’s implementing to get into character.

Read: WHAT WE KNOW ABOUT THE CATS MOVIE SO FAR

McKellen and Dench are set to appear alongside Jennifer Hudson, Taylor Swift, and James Corden in the big screen adaptation of the feline phenomenon.

McKellen last appeared on Broadway in No Man’s Land and Waiting for Godot, which played in repertory. He won a Tony Award for his work in Amadeus. Most recently, he appeared as the title character in King Lear in the West End.