OPINION
ANDERSON, PAUL H., Justice.
Daniel Maurstad received a 129-month sentence after pleading guilty to three offenses under a plea agreement. When Maurstad negotiated the plea agreement, both he and the state assumed he would have a two-point criminal history score, which would yield a 110-month presumptive sentence. But the presentence investigation identified a prior felony conviction and corresponding probationary sentence that the parties had not taken into account. The district court then assigned two additional criminal history points — one point for the prior felony conviction and one point for custody status. After sentencing, Maurstad petitioned for postconviction relief on the ground that he should not have been assigned the custody status point. He asked to be resentenced with a three-point criminal history score, which would reduce his sentence by a minimum of two months. The court denied relief, finding that Maurstad had waived or forfeited review by failing to object at sentencing.
[143]*143The Minnesota Court of Appeals reversed and remanded for resentencing. The court of appeals concluded that Maur-stad did not waive his right to appeal, that he was not required to show plain error in order to obtain appellate review, and that the district court erred by assigning the custody status point. The state petitioned for review of the following issues: (1) whether a defendant can waive or forfeit review of a criminal history score calculation; and (2) whether a custody status point may be assigned for offenses a defendant committed after discharge from an indeterminate probationary term. We affirm the court of appeals.
In July 2003, respondent Daniel Maur-stad was charged in Polk County with one count of first-degree controlled substance crime (manufacturing methamphetamine) and one count of conspiracy to manufacture methamphetamine. Ten weeks later, the state amended its complaint, adding two counts of first-degree controlled substance crime (possessing methamphetamine and possessing with intent to sell methamphetamine) and one count of failure to affix the appropriate tax stamps, labels, or other required indicia to methamphetamine. Three weeks after amending its first complaint, the state filed a separate complaint against Maurstad, alleging one count of second-degree controlled substance crime (selling methamphetamine). Six weeks later, the state again amended its first complaint, adding two assault counts.
One day before Maurstad was to go on trial for the seven counts listed in the amended complaint, his counsel moved the district court for a continuance and to permit his withdrawal as counsel. At a hearing on the motions, defense counsel stated that he and Maurstad had not been able to communicate effectively and to plan a defense. Counsel also stated that the state’s “numerous amendments” to its complaint had complicated efforts to prepare for trial and that he had not yet had a chance to talk with Maurstad about the recently-added assault charges. The court denied both motions, noting that the trial had already been postponed two or three times.
The following day, Maurstad entered three guilty pleas under a plea agreement resolving all pending charges. He pleaded guilty to one first-degree controlled substance crime, the second-degree controlled substance crime, and one misdemeanor assault. The state agreed to dismiss the remaining five counts against Maurstad. At the plea hearing, the state said Maur-stad would
be sentenced according to the Minnesota sentencing guidelines. We believe this will result in a presumptive commitment to prison for 110 months. All sentences will be imposed concurrent to one another.
(Emphasis added.) After the state recited several other terms of the plea agreement, the court asked defense counsel if the state’s understanding of the plea agreement was defense counsel’s understanding as well. Defense counsel replied that it was. At the end of the hearing, the court ordered a presentence investigation (PSI) report and set a sentencing date.
A corrections agent prepared and filed Maurstad’s PSI report. The report listed two prior convictions relevant to the determination of Maurstad’s criminal history score: a 1996 Marshall County conviction for third-degree burglary, and a 1996 Pennington County conviction for aiding burglary in the second degree. The agent assigned Maurstad four criminal history points — one point each for the Marshall County and Pennington County convictions, one point for “custody status,” and one point under Hernandez for Maurstad’s [144]*144second-degree controlled substance offense.1 The agent assigned the custody status point after concluding that the second-degree controlled substance offense occurred within the original term of probation that Maurstad received for the Pennington County conviction.
Neither the state nor defense counsel was aware of the Pennington County conviction before Maurstad’s PSI report was completed. Therefore, when the parties negotiated the plea agreement, they had anticipated that Maurstad would have two criminal history points, not four. With four criminal history points, the presumptive duration of Maurstad’s governing sentence increased from the 110 months contemplated in the plea agreement to 134 months.
Defense counsel did not raise any objection to the PSI report or sentencing worksheets before the sentencing hearing. At the beginning of the hearing, the district court asked defense counsel if there was a need for a hearing on the factual content of the PSI report. Counsel responded that he did not anticipate Maurstad’s criminal history score would be as high as it was. But counsel stated,
I do believe that our plea agreement * * * contemplated that there were no representations made as to what the criminal history points might ultimately be. So, I really don’t know that ethically [Maurstad] can contest any of those points, just note that it wasn’t anticipated that it would be that high.
After the state asked the district court to impose the presumptive guideline sentences concurrent to one another, the court asked whether defense counsel wished to comment. Defense counsel stated,
[Ajgain I’d like to note for the Court that we originally believed [Maurstad] was looking at a presumptive commit for 110 months on Controlled Substance Crime in the First Degree. I know that we had a plea agreement and, because of that, I really don’t have the ability to argue for something against the bargain that was struck. So, I guess I really can’t contest the imposition of the guideline sentence here.
Shortly thereafter, the state indicated that it would not object to the court imposing a sentence at the low end of the guidelines range — 129 months rather than 134 — for the first-degree controlled substance offense, which was the offense that governed the sentence.
Based on a four-point criminal history score, the district court imposed a 129-month sentence. Maurstad appealed this sentence to the court of appeals. He later moved to stay his appeal so he could pursue postconviction relief, and the court of appeals granted this motion. Maurstad then petitioned for postconviction relief, asking to be resentenced with the correct criminal history score. Maurstad argued that he should not have received a custody status point because he was not under “any form” of criminal justice system custody at the time he committed the current offenses.2
The record shows that Maurstad was sentenced by the Pennington County court [145]*145in February 1996. At the sentencing hearing, the court noted that aiding and abetting burglary in the second degree carried a maximum statutory penalty of 10 years in prison, a $20,000 fíne, or both. The court then stated, “it is hereby ordered that the imposition of the sentence is stayed and you [Maurstad] will be placed on supervised probation * * * for a period not to exceed the statutory maximum.” Forty-five months later, in November 1999, the same court issued an order discharging Maurstad from probation for this conviction. Maurstad argued to the post-conviction court that the Pennington County court had placed him on probation for a period not to exceed the statutory maximum of 10 years, which is different from placing him on probation for 10 years. He asserted that when he was discharged from probation in 1999, his probationary term and the “initial length of stay” imposed for the Pennington County conviction were over.
The state responded by asserting that Maurstad waived his right to challenge his criminal history score by “specifically agreeing] with the information set forth in the presentence investigation report and the sentencing guidelines worksheets.” The state further asserted that at a minimum, Maurstad forfeited postconviction review by failing to voice any objection to the PSI report or sentencing worksheets at or before sentencing, and therefore had to prove plain error — a standard Maurstad had not tried to meet.
The postconviction court denied Maur-stad’s petition for relief after declining to review his criminal history score calculation. The court found that because Maur-stad did not object to the PSI report or sentencing worksheets at the time of sentencing, he waived or, at a minimum, forfeited his right to request postconviction relief on the basis of his criminal history score calculation.
Maurstad appealed to the court of appeals, arguing that the district court erred when it assigned him a custody status point as a consequence of his Pennington County conviction.3 The state responded that the court of appeals should refuse to consider Maurstad’s criminal history score claim on the same procedural grounds the state raised before the postconviction court. As to the merits of Maurstad’s claim, the state argued that the sentencing guidelines are unambiguous and require assignment of a criminal history score custody status point because Maurstad committed the offenses for which he was sentenced within the 10-year probationary term imposed for the Pennington County conviction.
The court of appeals held that Maurstad had not waived his right to appeal the criminal history score calculation because a court may correct an “illegal sentence” at any time, and a defendant cannot waive the right to appeal an illegal sentence. State v. Maurstad, 706 N.W.2d 545, 549 (Minn.App.2005). The court also declined to apply plain-error analysis to “unobject-ed-to errors in sentencing” — i.e., Maur-stad’s criminal history score calculation— on the ground that a defendant has an “unwaivable statutory right” to appeal his sentence. Id. Finally, the court concluded that Maurstad was not under any form of custody when he committed the current [146]*146offenses, and therefore, held that the district court erred when it assigned a custody status point. Id. at 549-50.
The state petitioned for review of the court of appeals’ rulings on (1) whether a defendant can waive or forfeit review of a criminal history score calculation; and (2) whether a custody status point may be assigned when a court sentences a defendant upon conviction for an offense committed after discharge from an indeterminate probationary term.
I.
The state argues that Maurstad waived review of any issues relating to sentencing when he “specifically asked the district court to impose” the recommended sentences in the PSI report and .sentencing guidelines worksheets. The state argues in the alternative that Maurstad forfeited review of sentencing issues by failing to object to the report or worksheets at or before sentencing, and therefore must prove plain error in order to obtain review. Maurstad asserts that the state’s arguments are altogether inapplicable because a sentence based on an erroneous criminal score is an illegal sentence, and a defendant cannot waive or forfeit review of an illegal sentence. We first address the state’s waiver argument.
When a defendant has initially filed a direct appeal and then moved for a stay to pursue postconviction relief, we review the postconviction court’s decisions using the standard we would apply in a direct appeal. Santiago v. State, 644 N.W.2d 425, 439 (Minn.2002). Whether a defendant can waive or forfeit review of a criminal history score depends on how the rules of criminal procedure and certain related statutes are interpreted and is thus a question of law, which we review de novo. See State v. Nerz, 587 N.W.2d 23, 24-25 (Minn.1998).
The court of appeals concluded that a criminal defendant has an unwaivable statutory right to appeal a sentence and therefore cannot waive the right to appeal a criminal history score because this score is a key factor in calculating the defendant’s sentence. Maurstad, 706 N.W.2d at 549. We do not read our case law to support the court of appeals’ broad construction of a defendant’s right to appeal sentencing issues. See, e.g., State v. Henderson, 706 N.W.2d 758, 760 (Minn.2005) (recognizing that under certain circumstances, a defendant’s failure to object to sentencing issues at the time of sentencing will foreclose appellate review of those issues). What we have held is that a defendant may not waive sentencing issues in some contexts— for example, when a particular kind of sentencing error results in an illegal sentence. See, e.g., State v. Goff, 418 N.W.2d 169, 172 (Minn.1988); see also Minn. R.Crim. P. 27.03, subd. 9 (“The court at any time may correct a sentence not authorized by law.”). Thus, in Goff, we held that a defendant may challenge a criminal history score for the first time after sentencing, when the score includes a prior conviction obtained in violation of the defendant’s right to counsel. 418 N.W.2d at 172.
The court of appeals resolved the waiver issue in this case by focusing on the nature of Maurstad’s right to appeal his sentence. But we believe that the appropriate focus is on a different interest at stake — that is, the legislature’s stated public policy of achieving uniformity in sentencing. In State v. Misquadace, we acknowledged the legislature’s unequivocal statement that “[s ]entencing pursuant to the sentencing guidelines is not a right that accrues to a person convicted of a felony; it is a procedure based on state public policy to maintain uniformity, proportionality, rationality, and predictability [147]*147in sentencing.” 644 N.W.2d 65, 69 (Minn.2002) (quoting Act of May 6, 1997, eh. 96, § 1, 1997 Minn. Laws 694, 695) (codified at Minn.Stat. § 244.09, subd. 5 (2006)).
In order to effectuate the foregoing policy, sentences must be based on correct criminal history scores, as these scores are the mechanism district courts use to ensure that defendants with similar criminal histories receive approximately equal sanctions for the same offense. See Minn. Sent. Guidelines I (providing that one purpose of the guidelines is to “ensure that sanctions * * ⅝ are proportional to the severity of the offense of conviction and the extent of the offender’s criminal history ” (emphasis added)). We also note that imposition of the presumptive sentence under the Minnesota Sentencing Guidelines is mandatory absent additional findings. State v. Shattuck, 704 N.W.2d 131, 141 (Minn.2005); see also State v. Pince, 358 N.W.2d 435, 438 (Minn.App.1984) (requiring a sentence reduction when a miscalculated criminal history score leads to an unauthorized departure from the presumptive sentence), rev. denied (Minn. Mar. 6, 1985).
Based on the foregoing analysis, we conclude that because a sentence based on an incorrect criminal history score is an illegal sentence — and therefore, under Minn. R.Crim. P. 27.03, subd. 9, correctable “at any time” — -a defendant may not waive review of his criminal history score calculation. Accordingly, we hold that the postconviction court erred when it declined to consider Maurstad’s criminal history score claim on the basis of waiver.
II.
The state argues that even if Maurstad could not ivaive review of his criminal history score calculation by asking the district court to impose the recommended sentences in the PSI report and sentencing worksheets, he could and did forfeit the alleged calculation error by failing to object before or at the time of sentencing as “required” by Minn. R.Crim. P. 27.03, subd. 1(D), (F). The state further argues that under Minn. R.Crim. P. 31.02, we should apply plain error review to all unobjected-to errors, including criminal history score errors. Finally, the state asserts several policy-based reasons why we should require timely objections to preserve sentencing issues, including the incentive that such a requirement would provide for defendants to take district court proceedings more seriously and to make them as error-free as possible.
We agree with the state that criminal defendants should object to any errors in their criminal history score calculations at the time of sentencing, following the process set forth in Minn. R.Crim. P. 27.03, subd. 1(D), (F). We also agree that certain policies would be served by requiring timely objections to such errors. But these points of agreement do not alter our conclusion that the receipt of a mandatory presumptive sentence — which is necessarily predicated on a correct criminal history score under the Minnesota Sentencing Guidelines — is not a defendant’s right to waive, or, logically, forfeit. As we stated in State v. Osborne, 715 N.W.2d 436, 443 (Minn.2006), “forfeiture is nothing more than ⅜ ⅜ ⅜ waiver by silence,” and we see little logic in allowing a defendant to waive by silence a criminal history score calculation that he cannot waive by affirmative act.4
[148]*148Moreover, we cannot agree with the dissent that Minn. R.Crim. P. 31.02 qualifies the authority of courts to correct an illegal sentence at any time. The dissent acknowledges that a defendant cannot waive review of his criminal history score calculation because this calculation implicates our authority to correct an illegal sentence “at any time” under Rule 27.03, subd. 9. But the dissent nonetheless asserts that Maur-stad could and did forfeit — i.e., waive by silence — such review, and therefore, “the only review to which [he] is entitled” under Rule 31.02 is review for plain error. We disagree with the dissent’s application of Rule 31.02 in this case as a matter of policy. Specifically, we cannot now anticipate a case in which, after concluding that a defendant received an illegal sentence, we would decline to correct it because the error that led the district court to impose the sentence was not plain.
For the foregoing reasons, we conclude that a defendant cannot forfeit review of his criminal history score calculation, and accordingly, the plain error doctrine is inapplicable in this case.5 We therefore hold that the postconviction court erred when it declined to consider Maurstad’s criminal history score claim on the basis of forfeiture.
III.
We next address whether the district court erred in assigning Maurstad a custody status point under Minn. Sent. Guidelines II.B.2.C. Construction of the sentencing guidelines is a question of law that we review de novo. State v. Zeimet, 696 N.W.2d 791, 793 (Minn.2005). The goal of statutory construction is to effectuate legislative intent. Id. If the statutory language is plain and unambiguous, we do not engage in any further construction and instead look to the plain meaning of the statutory language. State v. Wukawitz, 662 N.W.2d 517, 525 (Minn.2003). But when the language of a criminal law is ambiguous, we construe it narrowly according to the rule of lenity. Zeimet, 696 N.W.2d at 794.
By the time Maurstad committed the current offenses, the Minnesota Sentencing Guidelines assigned a custody status point to offenders who “committed the [149]*149current offense within the period of the initial length of stay pronounced by the sentencing judge for a prior felony.” Minn. Sent. Guidelines II.B.2.C (emphasis added).6 Given this language, the parties are asking us to determine what “initial length of stay” the Pennington County District Court “pronounced” for the purposes of section II.B.2.C. We must make this determination in light of (1) the court’s sentencing pronouncement that, “it is hereby ordered that the imposition of sentence is stayed and you will be placed on supervised probation * ⅜ * for a period not to exceed the statutory maximum [of ten years]” (emphasis added); and (2) the fact that approximately 45 months after pronouncing this sentence and 34 months before Maurstad committed the current offenses, the same court discharged Maur-stad from probation for this conviction.
The state argues that section II.B.2.C of the sentencing guidelines is unambiguous, that Maurstad’s “initial length of stay” was 10 years, and that Maurstad’s discharge from probation after 45 months should have no bearing on his criminal history score calculation in relation to custody status. Despite the state’s initial contention that the applicable guidelines are unambiguous, we conclude that the state’s arguments center not on the unambiguous nature of the guidelines’ language, but rather on the intent behind that language. For example, the state surmises that the Sentencing Guidelines Commission’s purpose in amending section II.B.2 was to promote uniformity among Minnesota district courts in determining custody status, given widely varying practices for “early discharges” from probation. We agree with the state’s tacit recognition that the intent of the Sentencing Guidelines Commission as to section II.B.2.C is relevant here, because we conclude that the language of this section is ambiguous in light of the words the Pennington County District Court used in “pronouncing” Maurstad’s length of stay. See, e.g., State v. Colvin, 645 N.W.2d 449, 452 (Minn.2002) (stating that when the language of a criminal statute is ambiguous, legislative intent controls). Specifically, it is not clear how the phrase “initial length of stay” is to be applied in a case where a sentencing court places the defendant on probation for an indeterminate period.
In a 2002 report to the state legislature, the Sentencing Guidelines Commission summarized its amendment to section II. B.2.c by stating that
[a]n additional custody status point was given to some offenders. Offenders who are initially given probation for a period of years, but are subsequently discharged early from probation (before the time period initially pronounced by the court has run out), will receive a custody status point if the offender commits a new offense during the pronounced original period of probation.
Minn. Sent. Guidelines Comm’n, Report to the Legislature 3 (2002) (emphasis added). The report identifies the focus of section II.B.2.C as the offender who has been “discharged early from probation.” This focus [150]*150is further evidenced by the language of section II.B.2.C stating that “[t]his policy does not apply if the probationary sentence for the prior offense is revoked, and the offender serves an executed sentence.” Minn. Sent. Guidelines II.B.2.C (emphasis added). We therefore conclude that the phrase “initial length of stay” refers to the initial length of a defendant’s probationary term pronounced by the sentencing judge. Thus the question is — is Maurstad an offender who has been discharged early from probation and still within the initial length of a probationary term ordered for a prior conviction? We acknowledge that this question presents a close call, but we ultimately conclude that the answer is no. See Colvin, 645 N.W.2d at 452 (stating that when we interpret penal statutes, “all reasonable doubt concerning legislative intent should be resolved in favor of the defendant”).7
We conclude that if the Pennington County District Court had placed Maur-stad on probation for 10 years, he could have been “discharged early from probation” on any date before 10 years had passed and therefore still be within the “initial length of stay” when he committed the current offenses. But that is not what happened here. The Pennington County court instead placed Maurstad on probation “for a period not to exceed the statutory maximum [ten years].” (Emphasis added.) Under this sentencing order, the initial length of Maurstad’s probationary term was as short as zero years and as long as 10 years; thus, when Maurstad was discharged 45 months after sentencing, he was simply discharged from probation, not “discharged early from probation.” We therefore conclude that Maurstad’s current offenses were not committed within the probationary term pronounced by the court for the Pennington County conviction, and he should not have received a custody status point.
The state argues that placing indeterminate probationary terms outside the ambit of Minn. Sent. Guidelines II.B.2.C will render that section a nullity. Specifically, the state asserts that the purpose of the 2001 amendment to section II.B.2 was to eliminate disparate treatment of defendants based on how early they were discharged from probation for prior offenses, and treating determinate and indeterminate probationary terms differently necessarily frustrates this purpose. While the state’s argument has some merit, we find it unpersuasive because it ignores the possibility that determinate and indeterminate probationary terms may differ from one another in ways as fundamental as a defendant’s understanding of the exact terms of his sentence. It also assumes that specific word choices at sentencing do not or [151]*151should not matter; but they do matter, especially when a person’s liberty is at stake. An order requiring an offender to abide by certain conditions for a period “of 10 years” or face an executed sentence is arguably more onerous than an order to do the same for a period of “up to 10 years,” even though the offender may be discharged in fewer than 10 years under either order. See Minn.Stat. § 609.135, subd. 2(f) (2006) (providing that “[t]he defendant shall be discharged six months after the term of the stay expires, unless * * * the defendant has already been discharged”); State v. Rodriguez, No. A04-2192, 2005 WL 1669493, at *2 (Minn.App. July 19, 2005) (discussing the custody status of an offender whose sentence was stayed “for 40 years” and who was discharged from probation after approximately six years), rev. denied (Minn. Sept. 28, 2005).
We also acknowledge that the state has a colorable argument that any differences that may exist between determinate and indeterminate probationary terms cannot justify the impact that our interpretation of section II.B.2.C will have on offenders. Specifically, offenders with otherwise identical criminal histories who commit new offenses will be treated differently depending on whether they were previously discharged from determinate probationary terms or indeterminate probationary terms. We nonetheless conclude that absent a clear statement from the Sentencing Guidelines Commission that a probationary term of “up to” a specified number of years is the equivalent of a probationary term “of’ a specified number of years, offenders in Maurstad’s position should not receive a custody status point. Again, we base this conclusion on our belief that in a proceeding as fundamental to a person’s liberty as sentencing, the sentencing court’s word choices do matter.
Finally, we recognize that our conclusion may require probation officers to spend some additional time completing PSI reports and sentencing worksheets, to the extent that probation officers must now determine whether a particular defendant’s probationary term was determinate or indeterminate.8 But in light of the numerous appeals defendants have already brought on the basis of improperly calculated criminal history scores, the efficiency that the judicial system would realize from more thorough and accurate PSI reports may offset any additional burden on probation officers. Moreover, the responsibility of probation officers and district courts to ensure the accuracy of every defendant’s criminal history score is fundamental to achieving the state’s policy of uniform sentencing under the sentencing guidelines. We believe that this responsibility outweighs any administrative concerns advanced by the state.
For the foregoing reasons, we affirm the court of appeals holding that the district court erred in assigning Maurstad a custody status point under Minn. Sent. Guidelines II.B.2.C, and we remand to the district court for resentencing using a three-point criminal history score.
Affirmed and remanded to the district court for resentencing.
GILDEA and ANDERSON, G. BARRY, JJ., dissent.