*904On September 5, 2008, an Essex county grand jury returned an indictment charging the defendant with distribution of cocaine, second or subsequent offense, in violation of G. L. c. 94C, § 32A(b). A separate indictment charging the same was issued on September 24, 2008. The two offenses were joined, and the defendant’s trial began on November 30, 2009. On December 3, 2009, following a three-day jury trial, the defendant was found guilty on one count and was acquitted on the other.

Immediately following the jury’s verdict, a bench trial was conducted on the second and subsequent offense portion of the indictment. Before beginning, the judge engaged the defendant in an extensive jury waiver colloquy, during which the defendant explained that she could not read or write. The defendant did acknowledge, however, that she had the opportunity to discuss her decision with counsel, understood the consequences of waiving a jury, and was doing so voluntarily. Satisfied with the defendant’s oral waiver, the judge proceeded with the bench trial. No written waiver was ever filed with the court. At the close of the evidence, the judge determined that the Commonwealth had proved the defendant’s prior conviction beyond a reasonable doubt, and sentenced the defendant to a prison term of five to six years.

Discussion. The defendant contends that her conviction as a second or subsequent offender was invalid because she never signed a written waiver of her right to a jury trial. Indeed, our case law has established a “bright-line” rule under which a defendant’s jury waiver is only effective when a signed written waiver is filed with the court. Commonwealth v. Osborne, 445 Mass. 776, 781 (2006). The Commonwealth does not dispute the existence of such a rule. Rather, it suggests that the rule should not be enforced in this case, since the execution of a written waiver would have been an “empty gesture” given the defendant’s inability to read or write. We do not agree.

The defendant’s illiteracy does not, by any means, render the exercise of signing a written waiver meaningless. As the Supreme Judicial Court observed in Osborne, “the requirement of a signed, written jury waiver is an important protection provided by the Legislature for the benefit of a criminal defendant.” Id. at 780.2 The written waiver is particularly meaningful because it “create[s] a moment of pause and reflection on the part of a defendant that is concomitant with signing one’s name to a formal declaration relinquishing that right.” Ibid. “The solemnity of the written waiver and the formality of *905the colloquy also further the purposes of ‘assuring] that the ultimate decision regarding waiver of the jury be left to the defendant himself, not his counsel,’ Commonwealth v. Pavao, 423 Mass. 798, 803 (1996), and ensuring an evidentiary record that will foreclose most posttrial disputes about whether the waiver was knowingly and voluntarily made.” Commonwealth v. Osborne, supra at 781. Without having signed a written waiver, the defendant was not afforded these procedural safeguards. Accordingly, any waiver obtained was ineffective, and the defendant’s conviction was invalid. See ibid.

For the foregoing reasons, the judgment on the defendant’s underlying conviction of distribution of a class B substance is affirmed. The portion of the judgment that found the defendant guilty of a subsequent offense, pursuant to G. L. c. 94C, § 32A(b), is reversed, the finding is set aside, and the case is remanded for resentencing.

So ordered.