We must decide whether the district court abuses its discretion when it enhances a sentence based on the information contained in a Presentence Report the accuracy of which has not been challenged.
I
The U.S. Border Patrol apprehended Victor Romero-Rendon as he attempted to enter the United States illegally on April 28, 1998. Computer cheeks on him re*747vealed that he had been previously apprehended and deported by the Immigration and Naturalization Service (INS). The checks also uncovered that he had a criminal history in the United States. Romero-Rendon was indicted, and on August 31, 1998 pleaded guilty to one count of being a deported alien found in the United States, in violation of 8 U.S.C. § 1326.
The probation officer prepared, the Pre-sentence Report (“PSR”), in which he recommended that the district court find that Romero-Rendon’s base offense level be eight and that he have a Criminal History Category of II. The PSR also contained a recommendation that the base offense level be increased sixteen levels pursuant to U.S.S.G. § 2L1.2(b)(1)(A), which provides for such upward adjustment where the defendant-alien has been previously deported following a conviction for an aggravated felony, i.e., “a crime of violence (as defined in section 16 of Title 18 ... ) for which the term of imprisonment [is] at least one year.” See 8 U.S.C. § 1101(a)(43)(F). In turn, 18 U.S.C. § 16(a) defines “crime of violence” to mean “an offense that has as an element the use, attempted use, or threatened use of physical force against the person or property of another.” The PSR revealed that on March 31, 1992, Romero-Rendon pleaded guilty to assault with a firearm, a violation of California Penal Code § 245(a)(2), and received a five-year sentence. Hence the recommendation that a sixteen-level upward adjustment be made to his base offense level.
Romero-Rendon objected both prior to and at sentencing. He contended that in order to establish the previous conviction, the government must provide the sentencing judge with judgment or commitment documents from the previous conviction, his “rap sheet,” or deportation documents. In its response to the objections, the government did not provide any of the requested documentation. Thus Romero-Rendon argued there was insufficient evidence to prove that he had been convicted of an aggravated felony. At no time did Romero-Rendon allege that the PSR contained any inaccuracies, nor did he contend that the judge incorrectly characterized his previous offense as an aggravated felony. At sentencing, the district court judge rejected the objections and, relying on the PSR, found that Romero-Rendon had previously committed an aggravated felony, and enhanced his base offense level by sixteen levels.
Romero-Rendon filed this timely appeal.
II
As an initial matter, we must determine the appropriate evidentiary standard for establishing the conduct underlying this sentence enhancement. In most cases, the government bears the burden of proving factors enhancing a sentence by a preponderance of the evidence. See United States v. Torres, 81 F.3d 900, 903 (9th Cir.1996). “ ‘[W]hen a sentencing factor has an extremely disproportionate effect on the sentence relative to the offense of conviction,’ [however,] the government may have to satisfy a ‘clear and convincing’ standard.” United States v. Hopper, 177 F.3d 824, 833 (9th Cir.1999) (quoting United States v. Restrepo, 946 F.2d 654, 659 (9th Cir.1991) (en banc)).
Romero-Rendon argues that given the severity of the consequences of the enhancement in his case, the government should be required to prove the underlying offense by clear and convincing evidence, which it cannot do based only on the PSR. To support his argument for a heightened evidentiary standard in his case, Romero-Rendon relies primarily on Almendarez-Torres v. United States, 523 U.S. 224, 118 S.Ct. 1219, 140 L.Ed.2d 350 (1998), and Hopper. In Almendarez-Torres, the Supreme Court rejected the argument that a previous aggravated felony is an element of the offense of being in the United States after having been deported following an aggravated felony. See id. at 1222. Instead, the Court held that the previous *748aggravated felony, which increases the maximum penalty from two to twenty years, is a sentence enhancement. See id. As such, the government need not charge it in the indictment and thus need not prove its existence beyond a reasonable doubt. See id. The Court, however, explicitly left undecided “whether some heightened standard of proof might apply to sentencing determinations which bear significantly on the severity of sentence.” Id. at 1238.
Building on this opening left by the Supreme Court, Romero-Rendon bases his argument that the district court should have used a “clear and convincing” standard of evidence on Hopper. In Hopper, this court considered the issue of sentence enhancements for violent conduct in conjunction with the defendants’ conviction for conspiracy to obstruct the IRS. 177 F.3d at 829. Applying Restrepo’s “extremely disproportionate impact test,” the court concluded that the district judge should have required the government to prove the facts underlying the, enhancement by clear and convincing evidence where the seven-level enhancement increased the median point of the defendant’s sentencing range by 43 months from 24-30 months to 63-78 months. See id. at 833. Romero-Rendon’s sixteen-level enhancement increased the median of his sentencing range 39 months from 4-10 months to 41-51 months. Given the closeness between the severity of these enhancements it would seem at first blush that the correct standard of proof in this case is clear and convincing evidence.
There is a significant difference, however, between these cases. In Hopper, the defendants had been acquitted of the conduct on which the sentence enhancements were based. See id. at 832. Because they had pleaded not guilty to the conduct, the defendants necessarily disputed the accuracy of the factual basis of the enhancements. In contrast, Romero-Rendon has never challenged the accuracy of the PSR. As he never claims the PSR was wrong, there seems little need to apply a heightened evidentiary standard. We hold, therefore, that where the defendant does not challenge the accuracy of the information on which the judge bases the sentence enhancement, the preponderance of the evidence standard is the appropriate one regardless of the severity of the enhancement.1
United States v. Potter, 895 F.2d 1231 (9th Cir.1990), is not to the contrary. In Potter, this court considered the issue of enhancements in the context of 18 U.S.C. § 924(e)(1), which establishes mandatory minimum sentences for certain convicted individuals with three prior violent felonies. 895 F.2d at 1235. In Potter, the court noted that:
[I]t is important that the sentencing court and the appellate court be certain of the specific statutory sections under which the defendant previously was convicted; all too often a popular description of a prior offense will not enable the court to determine whether the relevant [enhancement applies].... Given the gravity of the penalty and Sherbondy’s emphasis on the statutory ele*749ments of the prior offense2, we conclude that a court should have copies of the judgments of conviction before it when determining whether a defendant has previously been convicted of “violent felonies” within the meaning of § 924(e)(1), although we do not foreclose the possibility that a defendant’s conviction under a specific statutory section or subsection might be established by some other form of clearly reliable evidence. A presentenee investigation report does not meet even the latter requirement.
Id. at 1238.
Read in light of the entire opinion, the preceding language cannot be interpreted to mean that a PSR alone can never support a finding of the aggravated felony underlying the enhancement where the consequences of that sentence enhancement are severe. As in Hopper, the defendant in Potter contested the basis for the sentencing enhancement, arguing here that the conduct for which he had been previously convicted did not constitute a “ ‘violent felony’ for purposes of enhancement under § 924(e).” Id. at 1236.
In Potter, the defendant had been convicted of possession of a firearm by a felon. See id. at 1232. Pursuant to 18 U.S.C. § 924(e), the district court enhanced his sentence for having three prior violent felonies. See id. As a factual basis for this enhancement, the court relied only on the PSR, which listed and described the prior felonies. See id. at 1233. On appeal, the defendant argued, in pertinent part, that he had committed an insufficient number of prior felonies to warrant the enhancement. See id. at 1235. The defendant contended in particular that his convictions for burglary and rape by force did not meet the definitions of violent felonies. This court reviewed the prior felonies de novo to determine whether the district court correctly concluded that the defendant had previously been convicted of three violent felonies. The court first looked at the burglary conviction. Relying only on the PSR’s specification of the statute under which the defendant had been convicted, the court determined that the burglary met the requirements of a violent felony. See id. at 1236. The court then turned to the conviction for rape by force. Here the court was stymied because the PSR did not specify under which section of the state penal code the defendant had been convicted. See id. at 1237. Although the PSR gave a short description of the offense, the sentencing court was required to look to the specific statutory definition of the offense of which the defendant was convicted. See Sherbondy, 865 F.2d at 1005-06, 1009-10. Because the PSR did not specify which statute the defendant had been convicted of violating, the court could not determine, based on the PSR, whether the defendant’s prior conviction fell under the definition of a violent felony:
However, the presentence investigation report, while noting Potter’s conviction for “Rape by Force,” does not mention the specific statutory section (and subsection) under which Potter was convicted. We are thus faced with the question of what constitutes the quantum of proof necessary to determine that a given prior conviction was for a “violent felony” under § 924(e)(1).
Potter, 895 F.2d at 1237 (emphasis added).
Only then did the court observe that a district court should have copies of the judgment before it determines whether a previous conviction qualifies as a violent felony. The court had already found that the defendant’s burglary constituted a violent felony by looking only to the PSR. *750The severity of the enhancement which concerned the court resulted as much from the burglary conviction as from the rape conviction. This analytical context makes clear that for the purposes of Romero-Rendon’s case, Potter held only that despite the grave consequences of the enhancement, evidence additional to an un-controverted PSR is necessary only if the PSR does not mention the statutory section of conviction.
Romero-Rendon can not benefit from the court’s holding that the PSR satisfies the higher level of certainty warranted by the severity of the enhancement provided that it specifies the statute of conviction. The PSR in this case specifies the statute under which he was convicted, and he has never alleged that the PSR is inaccurate. Thus, consistent with Potter, the unchallenged PSR in this case, the only evidence before the court, is sufficient evidence of the aggravated felony even where the enhancement is severe.
Ill
We have previously held that a district court may rely on an unchallenged PSR at sentencing to find by a preponderance of the evidence that the facts underlying a sentence enhancement have been established. See United States v. Marin-Cue vas, 147 F.3d 889, 895 (9th Cir.1998). The Sentencing Guidelines allow judges to rely at sentencing on “any information ... so long as it has sufficient indicia of reliability to support its probable accuracy.” Id. at 894-95 (quotations omitted). As the court wrote in Marin-Cuevas,
In this case, the only evidence presented by either side was the presentence report. As the district court explained, Marin-Cuevas has never denied he was convicted of those misdemeanors. He has argued only that the government failed to provide sufficient evidence. Because the only evidence before the sentencing court was the Presentence Report, the preponderance of the evidence sustains the district court’s finding.
Id. at 895.
In his effort to elude the grasp of Marin-Cuevas, Romero-Rendon argues (1) that in contrast to the sentencing court in Marin-Cuevas, the court here needed to know the specific statute of conviction in order to determine whether the offense met the definition of an aggravated felony; and (2) that the consequence of relying on the PSR in this case was more serious since it increased the maximum penalty from two to twenty years.3 Neither argument withstands scrutiny.4
*751Romero-Rendon argues that the PSR provides an insufficient basis for the sentence enhancement in this case because the district court must know the exact statute under which he was previously convicted in order to determine whether his conviction constituted an aggravated felony. He argues that in contrast, in Marin-Cuevas, the court did not need to know the exact statute of conviction to establish the number of criminal history points at issue; it needed to know only the amount of time served for each conviction.
Regardless of the strength of this distinction, it is beside the point here because the PSR includes the specific statute of conviction. The PSR stated that he pleaded guilty to a violation of California Penal Code § 245(a)(2). Thus the judge had all the information that Romero-Rendon claims he needed to decide that his prior conviction was an aggravated felony.5 Following Marin-Cuevas, & district judge does not abuse his discretion when he determines that the PSR is sufficiently reliable to calculate criminal history points. In Marin-Cuevas, the court held that the PSR had sufficient indicia of reliability because the probation officer obtained his information from a reliable source (the computerized criminal history) and had no reason to present anything other than the truth. See id. at 895. Similarly, in this case, there is no discernable reason why the officer who prepared the PSR should be dishonest, and the Report listed the sources of the probation officer’s information: computer checks from the FBI, CII, Bureau of Prisons, INS, and other state and federal government agencies. Thus it is difficult to see why the specification of a statute of conviction in a PSR would be any less reliable than the PSR’s description of the defendant’s criminal history endorsed in Marin-Cuevas. We hold that it is not and thus may be relied on by the sentencing judge.
Romero-Rendon also objects that the severity of the enhancement makes Marin-Cuevas inapplicable to his case. Marin-Cuevas did not limit its holding to instances in which the consequences of making findings based on a PSR are not severe. As we held above, regardless of the severity of the enhancement, where the defendant does not challenge the accuracy of the information in the PSR, the correct standard of proof is a preponderance of the evidence, the same standard the PSR met in Marin-Cuevas.
We are sympathetic to Romero-Ren-don’s concerns regarding the consequences of the severe sentence enhancement in this case and the concomitant need for accuracy. We have given these concerns serious consideration. But never does Romero-Rendon challenge the accuracy of the information in the PSR. Simply stated, it is difficult to see how the PSR is not sufficient evidence on which to base an enhancement if the defendant who knows he faces an additional 39 months in prison because of what it includes does not challenge its accuracy. Romero-Rendon’s failure to dispute the accuracy alleviates our concerns.
IV
Where the defendant does not challenge the basis for a sentence enhancement, the government need only prove the underly*752ing facts by a preponderance of the evidence. Under the circumstances, we need not reach the question of whether an unchallenged PSR provides evidence sufficient to support a sentence enhancement under the clear and convincing standard of proof. Because the unchallenged PSR is sufficient to prove the facts underlying the sentence enhancement by a preponderance of the evidence, the district court correctly relied on it in enhancing Romero-Rendon’s sentence.
AFFIRMED.
. At oral argument, Romero-Rendon submitted for our consideration Mitchell v. United States, 526 U.S. 314, 119 S.Ct. 1307, 143 L.Ed.2d 424 (1999), in which the Supreme Court held that a defendant who has pleaded guilty does not waive her right to remain silent at the sentencing hearing and that the sentencing judge may not draw an adverse inference from her silence. Presumably, Romero-Rendon would like us to draw from this holding the rule that no consideration can be given to the fact that he did not challenge the accuracy of the PSR. Mitchell can-nol be read for such a broad proposition. The government bears the burden of proving the facts underlying the enhancement. Where, as here, it submits the PSR as proof, and the defendant submits no contrary evidence, the only evidence before the sentencing judge is the uncontroverted PSR. In these cases, a judge may rely on it to establish the factual basis for the enhancement. To hold that Mitchell dictates otherwise would be to allow the defendant’s muteness effectively to rebut the government’s evidence.
. In United States v. Sherbondy, 865 F.2d 996 (9th Cir.1988), the court held that to determine whether a defendant’s prior conviction is a violent felony for the purposes of 18 U.S.C. § 924(e)(1) a court is to look to the statute under which the defendant was convicted, not the underlying facts of that conviction. Accord United States v. Lomas, 30 F.3d 1191 (9th Cir.1994) (holding that to determine whether a conviction constitutes an aggravated felony for the purpose of 8 U.S.C. § 1326, a court should look to the statutory definition of the crime, not to the underlying facts).
. Romero-Rendon never specifies which conclusion of Marin-Cuevas he finds inapplicable: that a judge does not abuse his discretion when he concludes that the PSR is sufficiently reliable to be used at sentencing, or that a judge does not clearly err when he makes a finding based on an uncontroverted PSR, which is the only item of evidence before him.
. Romero-Rendon also relies on an out of circuit case, United States v. Barney, 955 F.2d 635 (10th Cir.1992). In Barney, the court held that where an enhancement is based on a conviction obtained by a guilty plea, the court may look to the underlying facts contained in the indictment or information to determine whether the defendant's conduct fell within the Supreme Court’s definition of burglary. See id. at 639. The court stated that the sentencing court may not rely on the PSR for such information. It went on the say that, "To the extent that the district court considered convictions of Mr. Barney not noticed and only mentioned in the presentence report, it erred.” Id. at 640. Just what the court meant is unclear. This language seems to comport with our holding in Potter that where the sentencing court must go beyond the statute of conviction to look at the underlying facts, it should have more than the PSR. This interpretation is supported by a later Tenth Circuit case, United States v. Haslip, 160 F.3d 649 (10th Cir.1998) (holding that the propriety of a sentence enhancement is determined by looking to either the statutory definition of the underlying crime or, if this is not possible, the charging papers). Or, as the government argues, the court may only have meant that the district court errs if it relies on convictions "mentioned” in the PSR when the defendant has no "notice” that these convictions will be included in the calculation of *751violent felonies. In any case, because Romero-Rendon's appeal is controlled by Ninth Circuit law, it is unnecessary for us to determine what the Tenth Circuit meant.
. California Penal Code § 245(a)(2) makes it a crime punishable by up to four years in prison to “commitf ] an assault upon the person of another with a firearm....” Using this definition, a sentencing judge could conclude that this crime qualifies as an aggravated felony, i.e., a crime that has as an element the use of physical force against the person of another for which the term of imprisonment is at least one year. See 8 U.S.C. § 1101(a)(43)(F); 18 U.S.C. § 16(a).