U.S. Supreme Court justices rarely apologize from the bench. But on Monday, Justice Antonin Scalia did just that, and he probably had to. He had just called his longtime friend and colleague Ruth Bader Ginsburg “Justice Goldberg.”

Scalia was announcing his opinion in the immigration case Kerry v. Din, and as often happens, Ginsburg was in dissent. At the end of his summary of the case, Scalia said, “Justice Breyer filed an opinion dissenting, which justices Goldberg, Sotomayor and Kagan joined.”

Scalia did not immediately catch his own error. Justices looked around awkwardly, and it appeared that Chief Justice John Roberts Jr. leaned over to tell Scalia what he had said. “What did I say?” Scalia asked incredulously. When he finally understood, he said: “Goldberg's gone!” and added, “Sorry about that, Ruth.”