Police in Utah say an officer who pulled over legendary soul singer Gladys Knight was treated to an impromptu rendition of Happy Birthday.

Pleasant Grove police captain Mike Roberts says Knight was a passenger in the car stopped for speeding about 40 miles south of Salt Lake City on Wednesday night.

Officer Paul Rogerson was checking the driver’s license when the woman said she was with Gladys Knight, who is known as the Empress of Soul, on the way to a Church of Jesus Christ of Latter-day Saints choir performance. Knight is a Mormon convert, and Rogerson says she was speaking at the event.

Rogerson told the woman it was his birthday and Knight got out of the car and sang to him.

Police say Rogerson let the driver go with a warning.

Jeanteil Livingston, a spokeswoman for Knight, says the singer lives in Las Vegas but was in Utah for the choir rehearsal.

Three-time Grammy winners, the group Gladys Knight and the Pips was inducted into the Rock and Roll Hall of Fame in 1996. They became a success with songs like I Heard It Through the Grapevine and their classic Midnight Train to Georgia.