Taylor Swift closed out the U.S. leg of her sprawling 1989 tour in style last night by costuming herself as Frozen“s Olaf the Snowman and then singing a soaring duet of the Disney hit’s “Let It Go”; with Idina Menzel.

Sneaky Taylor teased the crowd in Tampa, Florida, saying: “I don’t know if you noticed but we have a Frozen theme going on here. If only Idina Menzel were here,”; before the star appeared on stage for the Frozen duet.