Appeal by defendant from a judgment of the County Court, Nassau County, rendered April 20, 1979, convicting him of criminal sale of a controlled substance in the first degree, criminal possession of a controlled substance in the first degree, and conspiracy in the first degree, upon a jury verdict, and imposing sentence. Judgment reversed, on the law, and new trial ordered. The facts upon which the convictions were based have not been considered. Derek Elms, who testified for the prosecution, had been indicted for the same crimes with which defendant was charged, and was named as a coconspirator in the indictment against defendant. As such, he was an accomplice as a matter of law (see People v. Korjus, 54 A.D.2d 720), so that his testimony had to be corroborated (see CPL 60.22), and the trial court erred in allowing the jury to decide whether he was an accomplice (see People v. Bell, 32 A.D.2d 781). An error such as this is necessarily harmful (see People v. Minarich, 46 N.Y.2d 970; People v. Jenner, 29 N.Y.2d 695), and requires a reversal. Damiani, J.P., O'Connor, Lazer and Rabin, JJ., concur.