Shawn Mendes is a big fan of Niall Horan, and the feeling appears to be mutual. Sunday night (November 20), Mendes shared an Instagram video of the two vocalists singing together backstage at the AMAs.

The pair teamed up for an impromptu rendition of Mendes's song "Mercy," which sounds amazing with Horan on harmonies. These two sing together so naturally, it's a bummer they haven't sat down and cranked out a whole album of duets yet.

Of course, if Mendes is to be believed, they're working hard on figuring out a time to book a studio together. Until then, enjoy this clip on repeat.