Katy Perry announced on Twitter that she wants her fans to vote on what her next single should be.

The star released snippets of two new tracks, Dark Horse and Walking On Air, and whichever songs has the most votes will be released on 17th September.

The winning song will be announced at tonight’s MTV Video Music Awards.

You can listen to the tracks here. To cast a vote, simply tweet using the hashtags #DarkHorseNOW or #WalkingOnAirNOW

Katy's new album PRISM will be released on 22nd September.