By Jessica Goodman
Updated July 14, 2015 at 12:50 PM EDT
Kris Connor/LP5/Getty Images

Taylor Swift united Republicans and Democrats at the Washington, D.C. stop on her 1989 world tour, but — surprise! — she also brought out one of her super talented best friends. Lorde stopped by to sing “Royals.”

Lorde and Swift have been BFFs since they bonded over burgers at Shake Shack, and in true Swiftie friendship fashion, they’ve supported each other’s work publicly and prominently. After Monday’s show, Lorde wrote on Twitter, “I’m gonna talk more about the show when I see it in full tomorrow. Be prepared for live tweeting and/or a long reference-heavy tumblr post but seriously, @taylorswift13 is the leader of a great and beautiful galaxy that I’d live in forever.” Same.

Here’s fan-shot footage of the performance.