Appeal by defendant from a judgment of the Supreme Court, Queens County, rendered February 16, 1977, convicting him of robbery in the first degree, upon a jury verdict, and imposing sentence. Judgment modified, on the law, by vacating the sentence. As so modified, judgment affirmed, and case remitted to Criminal Term for a hearing pursuant to CPL 400.21 and for resentencing. At sentencing, defendant was arraigned on a prior offense information arising out of a 1970 conviction in Queens County, upon his plea of guilty to robbery in the second degree. Defendant admitted entering the plea, but referred the sentencing court to his trial testimony that the guilty plea had been obtained through the refusal of prison officials to give him necessary medical treatment while incarcerated, for injuries suffered during jail riots. The sentencing court denied defendant's application for a hearing on this matter, adjudged him a prior felony offender, and sentenced him accordingly. Pursuant to the requirements of CPL 400.21, a hearing on the constitutionality of the prior robbery conviction was required (see People v. Hubbard, 71 A.D.2d 924). Therefore, we remit for a hearing and resentencing. We have considered the other points raised by the defendant and find that, in light of the overwhelming evidence of guilt, the errors noted, if any, were harmless beyond a reasonable doubt (see People v. Crimmins, 36 N.Y.2d 230). Hopkins, J.P., Damiani, Lazer and Cohalan, JJ., concur.