OPINION
ANDERSON, RUSSELL A., Chief Justice.
Respondent Douglas Alan Dettman pleaded guilty to one count of first-degree criminal sexual conduct. The district court sentenced him to 216 months in prison, a 72-month upward departure from the presumptive sentence. See Minn.Stat. § 609.342, subd. 2(b) (2004). While his case was pending on appeal, the United States Supreme Court decided Blakely v. Washington, 542 U.S. 296, 124 S.Ct. 2531, 159 L.Ed.2d 403 (2004). Based on Blakely, the court of appeals reversed Dettman’s sentence, holding that the upward sentencing departure was unconstitutional because it was based on judicial findings of fact. State v. Dettman, 696 N.W.2d 812, 813, 816 (Minn.App.2005). The court concluded that Dettman’s statements at his plea hearing could not constitutionally be used to support the departure “[bjecause Dett-man did not expressly waive his right to a jury determination of any fact supporting an upward durational departure.” Id. at 815. We affirm the court of appeals’ decision, holding that the upward departure violated Dettmaris Sixth Amendment right to a jury determination of facts supporting an upward durational departure. Because Dettmaris statements were not accompanied by an express, knowing, voluntary, and intelligent waiver of this right, they cannot be used to support the upward departure.
The facts giving rise to this appeal are relatively straightforward. In the late hours of May 12 or very early on May 13, 2003, Dettman called L.L.B. on the phone and asked her to come to his apartment to assist her boyfriend, who Dettman said was in trouble. When L.L.B. arrived at Dettman’s apartment, Dettman told her that her boyfriend had gone to purchase cigarettes, and L.L.B. entered the apartment to wait for his return. Dettman then grabbed a piece of duct tape and attempted to cover L.L.B.’s mouth with it. When L.L.B. fought back, Dettman restrained her and told her to be quiet or he would cut her throat. Dettman then instructed L.L.B. to get undressed and get on his bed, where he penetrated her vaginally [647]*647with his fingers and put his mouth on her vagina. According to the criminal complaint, Dettman also told police that he ordered L.L.B. to sit on his face and urinate into his mouth. At this point, the attack was interrupted by the Rochester police, who had responded to a report of a woman screaming for help in Dettman’s apartment. The police found L.L.B. naked on Dettman’s bed with blood around her mouth. The police also found a folding knife in Dettman’s pants pocket.
Dettman was arrested and charged with three counts of first-degree criminal sexual conduct and one count of kidnapping. On January 12, 2004, Dettman pleaded guilty to one count of first-degree criminal sexual conduct in exchange for dismissal of the other charges. At the plea hearing, the district court informed Dettman of his right to a jury trial on the issue of guilt, which he waived. Dettman then admitted luring L.L.B. to his apartment by telling her that her boyfriend was in trouble, performing multiple types of sexual penetration, and causing her to fear great bodily harm by threatening to slit her throat.
On March 1, 2004, the district court sentenced Dettman to 216 months in prison, a 72-month upward departure from the 144-month presumptive sentence provided in Minn.Stat. § 609.342, subd. 2(b). The court based the departure on the particular cruelty with which the offense was committed and the lasting psychological impact on the victim. With respect to particular cruelty, the court determined that Dettman (1) exploited his knowledge of L.L.B.’s relationship with her boyfriend to lure her to Dettman’s apartment, (2) subjected L.L.B. to multiple forms of penetration, (3) planned and prepared for the assault by pre-cutting duct tape that he planned to use to silence L.L.B., and (4) ordered L.L.B. to engage in especially repulsive acts.
Dettman appealed, and while his appeal was pending before the court of appeals, the United States Supreme Court decided Blakely v. Washington, 542 U.S. 296, 124 S.Ct. 2531, 159 L.Ed.2d 403 (2004). In Blakely, the Court reiterated its holding in Apprendi v. New Jersey, 530 U.S. 466, 120 S.Ct. 2348, 147 L.Ed.2d 435 (2000), that the Sixth Amendment requires that, other than a prior conviction, any fact that increases the penalty for a crime beyond the prescribed “statutory maximum” must be proved to a jury beyond a reasonable doubt. Blakely, 542 U.S. at 301-02, 124 S.Ct. 2531; Apprendi, 530 U.S. at 490, 120 S.Ct. 2348. Blakely reformulated the definition of “statutory maximum” as “the maximum sentence a judge may impose solely on the basis of the facts reflected in the jury verdict or admitted by the defendant.” Blakely, 542 U.S. at 303, 124 S.Ct. 2531. Thus, the rule established by the Apprendi line of cases is that “[a]ny fact (other than a prior conviction) which is necessary to support a sentence exceeding the maximum authorized by the facts established by a plea of guilty or a jury verdict must be admitted by the defendant or proved to a jury beyond a reasonable doubt.” United States v. Booker, 543 U.S. 220, 244, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005).
At the court of appeals, Dettman argued that the upward departure in his case violated the rule announced in Blakely because the departure was based on facts found by the district court. Relying on Blakely, the court of appeals concluded that the upward departure violated Dett-man’s Sixth Amendment right to a jury determination of aggravating sentencing factors and reversed and remanded for resentencing. Dettman, 696 N.W.2d at 816. The court of appeals noted that the [648]*648“findings supporting the upward durational departure were made solely by the district court,” and, under Blakely, Dettman was “entitled to a jury determination of any fact that increases the presumptive sentence.” Dettman, 696 N.W.2d at 815. The court concluded that a defendant must make an express on-the-record waiver of his right to a jury determination of aggravating sentencing factors before his statements at a plea hearing may be used to enhance his sentence. Id. “Because Dett-man did not expressly waive his right to a jury determination of any fact supporting an upward durational departure, his ‘admissions’ at the plea hearing should not be considered as such for purposes of the [admission] exception to the rule in Blakely.” Dettman, 696 N.W.2d at 815. We granted the state’s petition for review.
We have previously determined that Blakely announced a new rule of constitutional criminal procedure which applies to cases pending on direct review at the time Blakely was decided. State v. Houston, 702 N.W.2d 268, 273-74 (Minn. 2005); O’Meara v. State, 679 N.W.2d 334, 339 (Minn.2004). Because Dettman’s direct appeal was pending before the court of appeals when Blakely was decided, the substantive rule of Blakely applies retroactively to Dettman’s case. See Houston, 702 N.W.2d at 270, 274.
On appeal to this court, the state argues that Dettman forfeited appellate consideration of the alleged Blakely violation by failing to preserve the error at the district court. The state contends that most district court errors, if not properly preserved for appeal, are deemed forfeited and that any appellate review of the error must be under the plain error standard. In addition, the state argues that, irrespective of the standard of review, no Blakely error occurred in this case because Dett-man admitted the facts necessary to support the sentencing departure at his plea hearing and in statements made to police, which were later incorporated into the complaint. This case thus presents two Blakely-related questions: (1) whether Dettman forfeited appellate review of his Blakely claim by failing to object on Blakely grounds at the district court; and (2) whether the upward sentencing departure may constitutionally be based on statements Dettman made at his plea hearing and statements attributed to him in the criminal complaint.
I.
We first address the state’s contention that Dettman forfeited consideration on appeal of his Blakely claim because he failed to preserve the alleged Blakely error below. The state correctly notes that Dettman did not object at the district court to his sentence on the basis of a violation of his Sixth Amendment jury-trial right. Generally, a district court error not objected to at the district court is considered forfeited for purposes of appeal. See, e.g., State v. Blanche, 696 N.W.2d 351, 375 (Minn.2005); State v. Blom, 682 N.W.2d 578, 614 (Minn.2004). But here resolution of this question is controlled by our recent holding in State v. Osborne, 715 N.W.2d 436 (Minn.2006). In Osborne, we concluded that a defendant’s failure to object on Blakely grounds at the district court does not forfeit appellate review of an alleged Blakely error. Osborne, 715 N.W.2d at 446. Accordingly, we hold that Dettman did not forfeit appellate review of the alleged Blakely error in this case.
II.
We now turn to the state’s second argument — that no Blakely error occurred because Dettman admitted the facts used to enhance his sentence. The alleged [649]*649Blakely error in this case presents a constitutional question that we review de novo. See State v. Barker, 705 N.W.2d 768, 771 (Minn.2005).
Prom the Apprendi line of cases, it is clear that Dettman’s sentence could not constitutionally have been enhanced, beyond the maximum sentence authorized by the facts established by his guilty plea, based on judicial findings of fact.1 See Blakely, 542 U.S. at 303-05, 124 S.Ct. 2531; State v. Shattuck, 704 N.W.2d 131, 142-43 (Minn.2005). The district court’s imposition of an upward departure was permissible only if the facts authorizing the departure were either found by a jury beyond a reasonable doubt or admitted by Dettman. See Booker, 543 U.S. at 244,125 S.Ct. 738. Because it is undisputed that a jury did not find the aggravating factors used to enhance Dettman’s sentence, the narrow issue before us is whether Dett-man sufficiently admitted the facts authorizing the upward departure to satisfy the requirements of Blakely.
The state argues that Dettman admitted, both at his plea hearing and in police interrogation later incorporated into the complaint, facts supporting the upward departure, and therefore no Blakely error occurred. At his plea hearing, Dettman and his attorney had the following exchange:
Q. On May 12th or early May 13th did you place a phone call to a young woman with the initials L.L.B.?
A. Yes.
Q. And you asked her to come over to your apartment to help her boyfriend who was in trouble, is that correct?
A. Yes.
Q. She drove to your apartment and eventually came up to your apartment, is that correct?
A. Yes.
Q. When she got there her boyfriend was not at the apartment, is that correct?
A. Yes.
Q. You had told her that her boyfriend had gone out to get cigarettes, is that correct?
A. Yes.
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Q. You penetrated her vaginally with your fingers, is that correct?
A. Yes.
Q. You also put your mouth in her vaginal region, it that correct?
A. Yes.
In addition, Dettman made several statements to police that could support the district court’s upward departure if they constitute admissions on which an upward departure may constitutionally be based. Dettman told police that he planned for the assault by precutting a strip of duct tape to muzzle L.L.B. and by arranging pillows on his bed where he planned to have her lie. Dettman also told police that he ordered L.L.B. to urinate into his mouth.
[650]*650The state argues that these statements together constitute admissions supporting the district court’s finding of particular cruelty, which the court based on Dett-man’s exploitation of his knowledge of L.L.B.’s relationship with her boyfriend to lure her to Dettman’s apartment, his planning for the assault, his ordering L.L.B. to engage in especially repulsive acts, and the multiple forms of penetration. The state contends that Blakely does not require an express waiver of the right to a jury determination of aggravating sentencing factors before a defendant’s admissions may be used to enhance his sentence. In opposition, Dettman argues that a knowing, voluntary, and intelligent waiver of that right must precede the use of a defendant’s admissions to enhance his sentence, and, in the absence of such a waiver by Dettman, the upward departure in his case violates the Sixth Amendment. Dettman notes that he neither stipulated to the aggravating factors found nor consented to judicial fact finding on those issues.
The court of appeals concluded that a knowing, voluntary, and intelligent waiver of a defendant’s Sixth Amendment right to a jury determination of facts supporting an upward sentencing departure is required before the defendant’s statements may be used to enhance his sentence. Dettman, 696 N.W.2d at 815. Because Dettman did not expressly waive this right, the court held that his statements could not be used to enhance his sentence. Id.
In so holding, the court of appeals relied largely on an earlier court of appeals case, State v. Hagen, 690 N.W.2d 155 (Minn. App.2004). In Hagen, the court of appeals considered whether a defendant’s statements at a sentencing hearing constituted admissions that could be used to enhance his sentence. Id. at 157-58. The court reasoned that “[t]he effect of a defendant’s admission to an aggravating factor is to waive the defendant’s constitutional right to a jury trial on the sentencing issue.” Id. at 158. The court observed that a defendant’s waiver of his Sixth Amendment right to a jury trial must be knowing, intelligent, and voluntary. Hagen, 690 N.W.2d at 158-59. The court noted that although Hagen, as part of his guilty plea, had waived his right to a jury trial on the elements of the offense, he had not knowingly waived his right to a jury determination of aggravating sentencing factors because he was not informed of that right at the time of sentencing. Id. at 159. In the absence of an express, knowing waiver, the court held that Hagen’s statements could not be used to enhance his sentence. Id. at 159-60.
In addition, the court in Hagen noted that a defendant’s stipulation to an element of an offense must be supported by a waiver of the defendant’s right to a jury trial on that element. Hagen, 690 N.W.2d at 159 (citing State v. Berkelman, 355 N.W.2d 394, 397 (Minn.1984)). The court concluded that because the Blakely line of cases has “effectively dismantled the distinction between offense elements and sentencing factors,” a defendant may stipulate to a sentencing factor only after a waiver of the right to a jury trial on that factor. Hagen, 690 N.W.2d at 159.
In State v. Barker, we expressed approval of the court of appeals’ analysis and conclusion in Hagen. State v. Barker, 705 N.W.2d 768, 773 (Minn.2005). Our statements in Barker, however, were dicta, and we have not yet had occasion to dis-positively decide whether a knowing waiver is required before a defendant’s statements at his guilty-plea hearing may be used to enhance his sentence. With that issue now squarely before us, we hold that a defendant must expressly, knowingly, voluntarily, and intelligently waive his right to a jury determination of facts sup[651]*651porting an upward sentencing departure before his statements at his guilty-plea hearing may be used to enhance his sentence.2 Because Dettman did not knowingly waive this right, his statements at his plea hearing cannot be used to enhance his sentence, and the upward sentencing departure in his case violates the dictates of Blakely,
The Apprendi line of cases establishes the principle that a defendant’s constitutional right to a jury trial extends to any fact, other than the fact of a prior conviction, that is used to sentence the defendant. Apprendi, 530 U.S. at 490, 120 S.Ct. 2348; State v. Allen, 706 N.W.2d 40, 46 (Minn.2005); see also Blakely, 542 U.S. at 304, 124 S.Ct. 2531 (recognizing that the Sixth Amendment jury-trial right extends to all facts that the law makes essential to punishment); see also Apprendi, 530 U.S. at 477, 494 n. 19, 120 S.Ct. 2348 (noting that a criminal defendant is entitled to a jury finding of each element of the offense with which he is charged and that a fact used to enhance a sentence is the functional equivalent of an element of an offense). This right is grounded in the Sixth Amendment’s guarantee of the right to a jury trial and the requirement of proof beyond a reasonable doubt. See Apprendi, 530 U.S. at 477,120 S.Ct. 2348; see also Blakely, 542 U.S. at 305-06, 124 S.Ct. 2531 (“Our commitment to Apprendi * * * reflects * * * the need to give intelligible content to the right of jury trial. That right is no mere procedural formality, but a fundamental reservation of power in our constitutional structure.”). The use of a defendant’s statements to enhance his sentence thus entails a relinquishment of his Sixth Amendment right to a jury determination of facts supporting an upward sentencing departure.
It is well established that a defendant’s waiver of his right to a jury trial on the elements of an offense must be knowing, intelligent, and voluntary. Brady v. United States, 397 U.S. 742, 748, 90 S.Ct. 1463, 25 L.Ed.2d 747 (1970); State v. Ross, 472 N.W.2d 651, 653 (Minn.1991); State v. Pietraszewski, 283 N.W.2d 887, 890 (Minn.1979); see also Minn. R.Crim. P. 26.01, subd. l(2)(a). We see no principled basis for differentiating between a waiver of the right to a jury trial on the elements of an offense and a waiver of the right to a jury determination of aggravating sentencing factors.3 Both rights arise from the same Sixth Amendment guarantee, and the Supreme Court has said that a fact used to enhance a sentence is the “functional equivalent of an element of a greater offense.” Apprendi, 530 U.S. at 494 n. 19, 120 S.Ct. 2348; see also id. at 494, 120 S.Ct. 2348 (commenting that the distinction between elements and sentencing factors is “constitutionally novel and elusive”).
The dissent relies on language in Blakely that facts “admitted by a defendant” may be used to determine the defendant’s sentence to support its conclusion that Dettman’s plea hearing statements could constitutionally be used to enhance his [652]*652sentence. This reasoning begs the question of what constitutes an “admission” for Blakely purposes.4 In the more familiar context of the Sixth Amendment right to a jury trial on the elements of an offense, it is clear that only a defendant’s statement made after a knowing waiver of his right to jury trial constitutes an admission that dispenses with the state’s burden of proving offense elements to a jury. See Boykin v. Alabama, 395 U.S. 238, 242-43, 89 S.Ct. 1709, 23 L.Ed.2d 274 (1969) (distinguishing between a guilty plea and a mere confession and holding that a valid guilty plea requires a knowing waiver of the right to a jury trial); Minn. R.Crim. P. 15.01 (requiring a waiver of the right to a jury trial as part of a valid guilty plea). Without such a waiver, a defendant’s admissions are merely evidence that may be considered by a jury in determining guilt. See State v. Brown, 212 Ariz. 225, 129 P.3d 947, 952 (2006) (“Under the Sixth Amendment; a defendant who takes the stand at trial and admits the- existence of one or more of the elements of an offense does not thereby surrender his right to have the jury find all of the elements of the crime.”). The Supreme Court’s equation of sentencing factors with elements of an offense compels the conclusion that, just as a defendant’s admission to an element of an offense cannot be used in lieu of a jury finding unless the defendant knowingly waives his right to a jury trial on that element, so’ too must a defendant’s admission of a fact supporting an upward sentencing departure be accompanied by a knowing waiver of his right to a jury finding on that fact before the admission may be used to enhance his sentence.5
Furthermore, language in Blakely supports our conclusion that an express waiver is required before a defendant’s statements may be used to enhance his sentence. In Blakely, the Court stated,
nothing prevents a defendant from waiving his Apprendi rights. When a defendant pleads guilty, the State is free to seek judicial sentence enhancements so long as the defendant either stipulates to the relevant facts or consents to judicial factfinding. If appropriate waivers [653]*653are procured, States may continue to offer judicial factfinding as a matter of course to all defendants who plead guilty.
Blakely, 542 U.S. at 310, 124 S.Ct. 2531 (citation omitted). This passage indicates that a defendant’s stipulation to aggravating sentencing factors entails a waiver of his right to a jury trial on those factors.6 Long-standing Sixth Amendment jurisprudence dictates that such a waiver must be knowing, voluntary, and intelligent. See Brady, 397 U.S. at 748, 90 S.Ct. 1463; Ross, 472 N.W.2d at 653.
We are aware that several federal courts of appeals have upheld upward sentencing departures based on facts admitted at a sentencing hearing, a plea hearing, or in a plea agreement, without requiring an express waiver of the right to a jury determination of aggravating sentencing factors. See, e.g., United States v. Pittman, 418 F.3d 704, 709 (7th Cir.2005); United States v. Monsalve, 388 F.3d 71, 73 (2d Cir.2004); United States v. Saldivar-Trujillo, 380 F.3d 274, 279 (6th Cir.2004); United States v. Lucca, 377 F.3d 927, 934 (8th Cir.2004). But these cases do not contain any reasoning supporting their conclusion that a waiver is not necessary. Instead, the cases simply cite Blakely for the proposition that facts admitted by a defendant may be used to enhance a sentence. See, e.g., Saldivar-Trujillo, 380 F.3d at 279; Lucca, 377 F.3d at 934. We believe our approach is preferable to that of the federal circuits because our approach more appropriately takes into account long-standing principles regarding a defendant’s waiver of his jury-trial rights. We agree with the Colorado Supreme Court that a waiver requirement “furthers the central goal of Blakely, which was to correct a system ‘in which a defendant, with no warning in either his indictment or plea, would routinely see his maximum sentence balloon from as little as five years to as much as life imprisonment.’ ” People v. Isaacks, 133 P.3d 1190, 1195 (Colo.2006) (quoting Blakely, 542 U.S. at 311,124 S.Ct. 2531).
The state cites our decision in State v. Leake, 699 N.W.2d 312 (Minn.2005), in support of the argument that an express waiver is not required before a defendant’s plea hearing statements may be used to enhance his sentence. In Leake, the district court relied on a defendant’s statements during testimony to establish the factual basis for a guilty plea to an earlier offense to conclude that the earlier offense was a “heinous crime,” a fact then used to enhance the defendant’s sentence for the current offense. Id. at 319, 324-25. We held that the defendant’s plea hearing statements for the prior offense could be used to establish that the prior offense was a “heinous crime” and thus enhance the defendant’s sentence for the current offense, without requiring an express waiver of the right to a jury determination of aggravating sentencing factors. Id. at 324-25.
Leake is distinguishable from the ease at bar in two crucial ways and thus does not control resolution of the issue presented here. First, in Leake, the admission used to enhance Leake’s sentence was an admission to an essential element of a prior offense to which Leake had pleaded guilty — a “fact established by a plea of guilty.” Leake, 699 N.W.2d at 324; see [654]*654Booker, 543 U.S. at 244, 125 S.Ct. 738. As part of his guilty plea to the earlier offense, Leake had knowingly waived his right to a jury trial as to the elements of that offense. Here, the statements used to support Dettman’s enhanced sentence were not admissions to essential elements of the offense to which Dettman pleaded guilty. See Minn.Stat. § 609.342, subd. 1 (2004) (setting forth the elements of first-degree criminal sexual conduct).
Second, unlike this case, Leake involved Blakely’s prior conviction exception, “which appears to incorporate its own admission exception.” Barker, 705 N.W.2d at 774; see Leake, 699 N.W.2d at 323-25. The United States Supreme Court has expressly held that a defendant’s statements during a plea colloquy may be used to determine the character of a prior offense for purposes of Blakely’s prior conviction exception, without requiring a knowing waiver of the right announced in Blakely. Shepard v. United States, 544 U.S. 13, 16, 125 S.Ct. 1254, 161 L.Ed.2d 205 (2005); see also Leake, 699 N.W.2d at 325. Language in Shepard suggests that admissions used in the context of Blakely’s prior conviction exception need not be identical to admissions used to support aggravating sentencing factors unrelated to the fact of a prior conviction. See Shepard, 544 U.S. at 24-25, 125 S.Ct. 1254 (plurality opinion); Barker, 705 N.W.2d at 775. Because Dett-man’s statements were not used to support the fact of a prior conviction, our conclusion in Leake is inapplicable here.
Dettman’s waiver of his right to a jury trial on the issue of guilt cannot be interpreted as a waiver of his right to a jury determination of aggravating sentencing factors. Dettman knowingly waived his jury-trial right as to the elements of first-degree criminal sexual conduct.7 However, because Dettman was sentenced before Blakely was decided, he could not have known that he had a right to a jury determination of the facts used to enhance his sentence — facts going beyond the elements of first-degree criminal sexual conduct— and thus did not knowingly waive that right.8 See Minn.Stat. § 609.342, subd. 1; Brown, 129 P.3d at 950-51.
[655]*655In sum, in the absence of a knowing waiver of his Sixth Amendment right to a jury determination of facts supporting an upward sentencing departure, Dett-man’s statements at his plea hearing cannot be used as admissions to enhance his sentence.9 Additionally, Dettman’s statements to police, later incorporated into the complaint, are not admissions on which a judge may base a sentence enhancement because they were not made for purposes of dispensing with the state’s burden of proof after a knowing waiver of Dettman’s jury-trial rights. Accordingly, because the upward departure in this case was based on facts neither found by a jury nor properly admitted by Dettman, we hold that the departure violated Dettman’s Sixth Amendment rights.
III.
Having determined that the upward sentencing departure in this case violated the rule established in Blakely, we now consider whether this error was harmless. See Osborne, 715 N.W.2d at 447; see also Washington v. Recuenco, — U.S. —, 126 S.Ct. 2546, 2553, - L.Ed.2d - (2006) (concluding that Blakely errors are subject to harmless error analysis). Because the erroneous departure increased the length of Dettman’s sentence by 72 months and because we cannot say with certainty that a jury would have found the aggravating factors used to enhance Dettman’s sentence had those factors been submitted to a jury in compliance with Blakely, we conclude that the Blakely error was not harmless. See Osborne, 715 N.W.2d at 447. Accordingly, we affirm the court of appeals and remand to the district court for resentencing consistent with State v. Shattuck, 704 N.W.2d 131, 148 (Minn.2005). Because we affirm the court of appeals’ reversal of Dettman’s sentence based on the Blakely error, we do not reach Dettman’s alternative argument that the facts of this case do not present substantial and compelling circumstances justifying an upward sentencing departure.
Affirmed.