Pharrell Williams is threatening legal action against Donald Trump over the use of his hit “Happy.”

On Saturday (Oct. 27), the President played Pharrell’s hit single at a Midwest rally, just hours after the deadly Tree of Life synagogue shooting in Pittsburgh. In response, Pharrell has sent a cease and desist letter to Trump via his lawyer.

“On the day of the mass murder of 11 human beings at the hands of a deranged ‘nationalist,’ you played his song ‘Happy’ to a crowd at a political event in Indiana,” writes attorney Howard King. “There was nothing ‘happy’ about the tragedy inflicted upon our country on Saturday and no permission was granted for your use of this song for this purpose.”

King says that Williams has not and will not grant Trump permission to “publicly perform or otherwise broadcast or disseminate any of his music,” and says that the use of “Happy” without his consent violates copyright infringement.

As The Hollywood Reporter points out, this is not the first time Trump has received a cease and desist from a musician. Prince’s estate, Steven Tyler, R.E.M., and Queen have all protested Trump’s use of their music at his events.

Pusha-T also voiced his support for Pharrell by reposting the cease and desist letter on Instagram. “Just so everyone’s clear… @pharrell #CeaseAndDesist ,” he wrote.