On June 22, 1989, Alan R. Lange pleaded guilty to theft of government mail by a postal employee, in violation of 18 U.S.C. § 1709. The District Court determined the appropriate total offense level under the Sentencing Guidelines to be seven, comprised of a base offense level of four, a special offense characteristic of one, and a two-level increase for more than minimal planning. Lange was sentenced to four years of probation, including sixty days in residence at the Fort Des Moines Residential Correction Center. He was also ordered to perform fifty hours of community service and pay $645 in restitution. In this appeal, the government challenges the District Court’s application of the Sentencing Guidelines. It claims that the Court erred in refusing to adjust the offense level upward for obstruction of justice and abuse of a position of public trust. We reverse and remand for resentencing.
Lange was a mail handler with the United States Postal Service from May 1982 to December 1988. He dealt with express and certified mail one day a week. After cash was found to be missing from express and certified mail on the days Lange handled that mail, postal inspectors confronted Lange and found stolen cash and mail on his person. As part of an agreement with the government, Lange pleaded guilty to stealing $70 from an express letter. Lange also entered into a Stipulation of Facts in which the government claimed that Lange opened numerous other letters and stole a total of $645. Lange maintained in the Stipulation of Facts, and at the plea hearing, that he stole only $90 from three pieces of mail.
A Presentence Report, prepared by the United States Probation Office, concluded that Lange stole the $645 alleged by the government. In a filing attacking the findings in the Presentence Report, Lange repeated his claim that he took only $90. He made the same statement under oath at the time of his guilty plea. At sentencing, however, Lange confessed to the Court that he had lied about the extent of his thefts, and he admitted responsibility for the additional thefts which he had previously denied. Lange had lied earlier, he said, in order to minimize his sentence under the Sentencing Guidelines. Tr. 91-92.
The government requested that Lange be assessed an additional two points under the Sentencing Guidelines for obstruction of justice, pursuant to U.S.S.G. § 3C1.1. The District Court declined to do so, stating that
there has not been a showing that there was an intentional obstruction of justice by the failure of the defendant to state truthfully what had occurred at the plea *709proceeding or other earlier proceedings. The Court, in particular, finds that there was not, in fact, obstruction, and the Court does not find that the statements that were not true were designed ... to obstruct to bring him to justice.
Tr. 122.
We believe it was error for the District Court not to assess the additional points for obstruction of justice. U.S.S.G. § 3C1.1 provides that “[i]f the defendant willfully impeded or obstructed, or attempted to impede or obstruct the administration of justice during the investigation or prosecution of the instant offense, increase the offense level by 2 levels.” The Commentary to § 3C1.1 further clarifies the intended application of the section: it is to “provid[e] a sentence enhancement for a defendant who engages in conduct calculated to mislead or deceive authorities or those involved in a judicial proceeding....” Lange admitted both the falsity of his previous statements and the purpose of those statements — to receive a lighter sentence.1 Accordingly, Lange should have received the two-level enhancement.
We do not hold that a two-level increase for obstruction of justice is automatically required anytime a defendant lies during an investigation or prosecution. Rather, the falsehood must be material. The Application Notes to U.S.S.G. § 3C1.1 include “testifying untruthfully or suborning untruthful testimony concerning a material fact” and “furnishing material falsehoods to a probation officer in the course of a presentence or other investigation for the court” in a list of conduct which may provide a basis for the two-level enhancement. Lange admitted that he lied about the extent of his thefts. The value of stolen property was clearly a material fact in these judicial proceedings, because under the applicable Guideline for theft, U.S.S.G. § 2B1.1, the offense level increases as the value of the property taken increases. Therefore, Lange’s repeated misrepresentation was material, deserving of the additional two points. Cf. United States v. Blackman, 904 F.2d 1250, 1260 (8th Cir.1990) (dissenting opinion) (Commission intended to punish only material falsehoods).
Lange relies on Application Note 1 to U.S.S.G. § 3C1.1, which reads as follows:
This provision is not intended to punish a defendant for the exercise of a constitutional right. A defendant’s denial of guilt is not a basis for application of this provision.
We read the phrase “denial of guilt” to refer to a defendant’s constitutional right to put the government to its proof by pleading not guilty to the offense charged. A defendant who initially pleads not guilty and then changes his plea, admitting guilt under oath, may not be assessed the two-level enhancement on the theory that his false not-guilty plea was an obstruction of justice. Moreover, a defendant faced, as Lange was, with allegations of conduct outside the offense charged that would enhance his potential penalty under the Guidelines has a right to assert his Fifth Amendment right not to incriminate himself, or simply to stand mute. That is not what Lange did. He deliberately lied, both to the Probation Office and under oath in open court, knowing that the truth would adversely affect his status under the Guidelines. There is no constitutional right to lie.
The government also argues that the District Court erred in not enhancing the offense level for abuse of a position of public trust, § 3B1.3. That section provides for a two-level enhancement “[i]f the defendant abused a position of public or private trust, or used a special skill, in a manner that significantly facilitated the commission or concealment of the offense_” The section is not to be applied, however, “if an abuse of trust or skill is included in the base offense level or specific offense characteristic.”
The District Court refused to apply the abuse-of-public-trust enhancement because *710it believed “that in all postal theft cases, trust is built into the guidelines and the statute and cannot be added to.” Tr. 121— 22. - While the underlying criminal statute does assume an abuse of public trust, because it specifically addresses theft of government mail “entrusted” to a postal employee, our understanding of the caveat to application of § 3B1.3 is different from the District Court’s. The enhancement is not to be applied when the base offense level or a specific offense characteristic takes into account abuse of public trust. Under the Guidelines, the base offense level for any theft is four. U.S.S.G. § 2B1.1. Lange was assessed an additional point as a special offense characteristic (for theft over $100 but less than $1,000), which was calculated solely from the amount stolen. 18 U.S.C. § 1709 provides a maximum sentence for theft by a postal employee (five years’ imprisonment, a $2,000 fine, or both), but the statute does not otherwise affect the base offense level or specific offense characteristic under the Sentencing Guidelines.
The question then remains whether the thefts committed by Lange were an abuse of a position of public trust. The Application Notes to § 3B1.3 state that “[t]he position of trust must have contributed in some substantial way to facilitating the crime and not merely have provided an opportunity that could as easily have been afforded to other persons.” Accordingly, the adjustment would not apply “to an embezzlement by an ordinary bank teller.” Lange argues that his thefts were like “embezzlement by an ordinary bank teller” — any postal employee may steal from the mails. We disagree. Lange had direct access to express and certified mail as a substitute handler one day a week. Postal employees in general did not have the same opportunity as Lange to steal from this type of mail and conceal the crime, and the kinds of mail involved are especially sensitive and probably more likely to contain things of value than mail in general. We think the enhancement provided in § 3B1.3 is aimed at this conduct, and the District Court should have added two points to Lange’s offense level.2
In sum, the District Court erred by not adding a two-level enhancement for obstruction of justice, pursuant to U.S.S.G. § 3C1.1, and another two-level enhancement for abuse of position of public trust, pursuant to U.S.S.G. § 3B1.3. The sentence is reversed, and the cause is remanded for resentencing in a manner not inconsistent with this opinion.
. Lange testified that "[t]he mail that had my prints on it and what we had stipulated to, the way I understood it that if I come forward with that and it went through, that the federal guidelines for that offense was so much lighter than what if I had come forward and said, ‘Well, I did all of it.’ And I just — that's what I did. I just — I did it.” Tr. 91.
. We decline to address the government’s argument that the District Court erroneously held the government to a higher standard in proving enhancing factors than the defendant in proving mitigating factors. There is no factual dispute in this appeal, and we reverse the District Court on its failure to apply U.S.S.G. §§ 3C1.1 and 3B1.3 as a matter of law. See United States v. Werlinger, 894 F.2d 1015, 1016 (8th Cir.1990) (question whether § 3C1.1 applies to defendant’s conduct calls for interpretation of the scope of the Guidelines; therefore, it is a question of law which this Court may review de novo).