Judgment, Supreme Court, New York County (Leff, J., at plea and sentence; Goldman, J., on suppression motion), rendered on June 19,1979, convicting defendant of attempted criminal possession of a dangerous weapon in the third degree and sentencing him as a predicate felony offender to an indeterminate term of one and one-half to three years, unanimously modified, on the law, to vacate the sentence and remand for further proceedings pursuant to CPL 400.21 (subd 3). We are not persuaded that defendant’s acknowledgment at the time he entered his plea that he was to be sentenced as a predicate felony offender constituted a waiver of his right to controvert the predicate felony statement in accordance with the procedures set forth in CPL 400.21. It is appreciated that a Judge who enters a negotiated plea on the basis of the express understanding of the defendant that he is to be sentenced as a predicate felony offender should regard as an imposition on the court defendant’s effort to dispute that status on the day of sentence. We note that procedural steps are available to the Judge taking the plea to secure an effective waiver of the right to challenge the predicate felony statement. (See People ex rel. Colon v Reid, 70 AD2d 893; People v Bryant, 47 AD2d 51.) The record here seems to us to fall short of that which would be required to secure such a legally effective waiver. Accordingly, the sentence is vacated and the case remanded for further proceedings in accordance with CPL 400.21 (subd 3). We intimate no view whatever as to the merit of the defendant’s challenge to the predicate felony statement. And, of course, if it should be determined that defendant was not a predicate felony offender, it would clearly be appropriate under the circumstances for the District Attorney to move to vacate the plea that was entered into on the understanding that he would be sentenced as one. Concur — Sandler, J. P., Carro, Lupiano, Bloom and Milonas, JJ.