Hoards of classic rock fans recently flocked to Indio, California for Desert Trip, a two-weekend music festival featuring legendary ’60s and ’70s acts Paul McCartney, the Rolling Stones, The Who, Boy Dylan, Neil Young and Pink Floyd’s Roger Waters.

During McCartney’s nearly three-hour set on Saturday (October 15), the former Beatle brought out a surprise guest to perform “FourFiveSeconds”—Rihanna. The pair sang their 2015 collaboration with Kanye West to the (mostly) over 50 crowd. Watch it above.