While Katy Perry sweeps through Europe on her Witness World Tour, she's evidently made a stop in Stockholm to reunite with a longtime collaborator. Perry posted a video on her Instagram story Sunday (June 10) in which she's seen with Max Martin, the Swedish songwriter who's had a hand in penning many of her biggest hits. Their antics raise eyebrows about whether or not Perry is back in the studio.
Over the course of her career, Martin has co-written a slew of tracks for Perry, dating back to her 2008 breakout One of the Boys. He's responsible for many of her No. 1 hits, including "I Kissed a Girl", "California Gurls," "Teenage Dream," "E.T.," "Last Friday Night (T.G.I.F.)," "Wide Awake," "Roar" and "Dark Horse."