(Photo credit: Katy Perry/Instagram)

Talk about fireworks!

On Independence Day, Katy Perry joined John Mayer at Philadelphia's Fourth of July Jam, where he performed. Next to a shot of the two wearing coordinated outfits, the "Firework" singer wrote, "Whose broad stripes and bright stars?!"

Perry, 28, and Mayer, 35, dated for several months before they split in March. Afterward, Perry explained their connection to Vogue magazine.

"I was madly in love with him. I still am madly in love with him," she said. "Beautiful mind, tortured soul. I do have to figure out why I am attracted to these broken birds."

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However, on June 24, they seemed very much back together at the Friars Foundation Awards Gala in New York City.

"They were smooching and rubbing one another's backs," a source told ABC News. "And Katy had her arm around John at one point."