Watch Inside Llewyn Davis star Oscar Issac sing a folk version of Katy Perry’s "Roar"

The Coen brothers' faux folk music film, Inside Llewyn Davis,

gets a wide release today, so now seems like a good time to watch star Oscar Issac perform a folksy take on Katy Perry's pop hit "Roar." The actor stopped by Late Night With Jimmy Fallon last week to promote the movie and growled out an acoustic cover that makes the song sound about as gritty and world-weary as a number-one pop single can sound. Featuring Jimmy Fallon on harmonies. Watch the video below.