Bernard J. Drapeau, Jr., appeals his conviction for distributing a controlled substance and possessing a controlled substance with the intent to distribute, and his sentence of 324 months’ imprisonment and three years’ supervised release. We affirm Drapeau’s conviction, but vacate his sentence and remand for resentencing in light of United States v. Booker, — U.S. -, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005).
*873I.
Drapeau was convicted based on information the Northern Plains Safe Trail Drug Enforcement Task Force (“Task Force”) gathered from a controlled drug transaction in Fort Thompson, South Dakota. The transaction was carried out on April 20, 2002, by a confidential informant, Kristy Big Eagle, working with three Task Force agents. Big Eagle made a recording of the transaction with a hidden audio microphone provided by the agents.
On November 13, 2002, Drapeau was indicted on two drug counts: distribution of a controlled substance and possession of a controlled substance with intent to distribute, in violation of 21 U.S.C. .§ 841(a)(1). Task Force agents arrested Drapeau in Fort Thompson on November 15, and promptly advised him of his Miranda rights. Drapeau at first stated that he did not want to talk to the agents. The agents then transported Drapeau to Hughes County Jail in Pierre, about sixty miles away. During the trip from Fort Thompson to Pierre, Drapeau admitted using and distributing methamphetamine. The following day, November 16, Drapeau gave agents a more detailed history of his involvement in drug trafficking, naming other persons from whom he had purchased drugs and specifying the quantities purchased. He also admitted selling methamphetamine to Big Eagle on.six occasions.
At Drapeau’s trial on April 1 and 2, 2003, Big Eagle and three Task Force agents gave testimony. Big Eagle testified that she purchased methamphetamine from Drapeau during the controlled transaction, and the jury heard the audio tape of the episode. One of the agents recounted Drapeau’s admission on November 16 that he had sold drugs to Big Eagle on six occasions. The jury found Drapeau guilty on both counts.
Drapeau was sentenced on January 12, 2004. Although the jury was required to find only that Drapeau distributed and possessed with intent to distribute a “detectable amount” of drugs, the court determined that Drapeau was responsible for 1.721 kilograms of methamphetamine and that his base offense level was 34." (S. Tr. 34). The court applied a two-level adjustment for possession of a dangerous weapon, USSG § 2Dl.l(b), (id. at 35), which resulted, in a total offense level of 36. After finding that Drapeau’s criminal history category was VI, the court sentenced Dra-peau at the low end of the applicable sentence range of 324 to 405 months’ imprisonment.
A.
Drapeau advances four arguments why his conviction should be reversed. First, he contends that the district court erred in denying his motion to suppress statements he made to Task Force agents following his arrest. The district court denied Drapeau’s motion to suppress his statements, adopting the report and recommendation of the magistrate judge who conducted a hearing on the motion. We review the district court’s findings of fact for clear error and the legal conclusions de novo. United States v. Thom, 375 F.3d 679, 683 (8th Cir.2004).
Drapeau argues that his statements were obtained in violation of his rights under Miranda v. Arizona, 384 U.S. 436, 86 S.Ct. 1602, 16 L.Ed.2d 694 (1966), because they were a product of the arresting agents’ failure to honor scrupulously his “right to- cut off questioning.” See Michigan v. Mosley, 423 U.S. 96, 104, 96 S.Ct. 321, 46 L.Ed.2d 313 (1975); United States v. Thompson, 866 F.2d 268, 271 (8th Cir.1989). In Mosley, the Supreme Court clarified that “the admissibility of statements obtained after the person in custody *874has decided to remain silent depends under Miranda on whether his ‘right to cut off questioning’ was ‘scrupulously honored.’ ” Mosley, 423 U.S. at 100, 96 S.Ct. 321 (quoting Miranda, 384 U.S. at 473-74, 86 S.Ct. 1602). The Mosley analysis applies once a suspect in custody has “effectively asserted his right to remain silent.” Thompson, 866 F.2d at 270.
We believe this case is comparable to Thompson, where the suspect initially told interrogating agents that he would “sleep on it” and would talk “tomorrow,” but later volunteered that he wanted to “wait a little while before I’m interviewed.” Thompson then signed a waiver of rights form and answered questions. We held that even assuming Thompson’s initial statement was a request to defer questioning until “tomorrow,” his initial decision to remain silent was reversed by his later volunteered statements. .Therefore, Thompson had not “effectively asserted” his right to remain silent, and Mosley did not apply.
In this case, the district court found that after agents advised Drapeau of his Miranda rights, Drapeau responded by saying he “did not want to talk to agents at that time.” (Tr. of. Bench Dec. at 6). Shortly thereafter, however, Drapeau “initiated a conversation with agents” during the car ride to Pierre. (Id.) The conversation began as a general one, touching on hunting, fishing, children, and Fort Thompson. Drapeau then “brought up the facts that his parents were ill,” and “that he did not want .to go to prison” and “expressed a willingness to cooperate and help law enforcement out.” (Id. at 7.) The district court found that Drapeau’s testimony, to the extent it conflicted with these findings, was not credible (id. at 8), and this credibility finding is not clearly erroneous.
Drapeau’s unprompted offer of cooperation was “an effective reversal” of his previously expressed desire not to talk to agents “at that time.” See Thompson, 866 F.2d at 271. His actions do not represent a “clear, consistent expression of a desire to remain silent.” Id. at 272. We therefore hold that Drapeau did not effectively assert his right to remain silent, and we need not address whether his right to remain silent was “scrupulously honored” under Mosley.
B.
Drapeau’s second argument is that the district court impermissibly allowed the jury to hear testimony from Big Eagle that she previously purchased drugs from Drapeau. Federal Rule of Evidence 404(b) makes inadmissible “[ejvidence of other crimes, wrongs, or acts.... to prove the character of a person in order to show action in conformity therewith,” but permits the introduction of such evidence to prove motive, opportunity, intent, preparation, plan, knowledge, or identity, or to show absence of mistake or accident. We review a district court’s admission of evidence under Rule 404(b) for abuse of discretion. United States v. Crenshaw, 369 F.3d 977, 998 (8th Cir.2004).
Drapeau argues that Big Eagle’s testimony was inadmissible under Rule 404(b), because it was offered only to show Drapeau’s propensity to distribute drugs. Our circuit requires that evidence meet four criteria for admissibility under Rule 404(b). United States v. Williams, 308 F.3d 833, 837 (8th Cir.2002). First, the evidence must be relevant to a material issue. Id. Second, it must be similar in kind and “not overly remote in time to the charged crime.” Id. Third, the evidence must be “supported by substantial evidence.” Id. Last, its probative value must outweigh any unfair prejudice. Fed. R.Evid. 403; Williams, 308 F.3d at 837.
*875Applying these criteria, we conclude that the district court did not abuse its discretion in permitting Big Eagle’s testimony regarding Drapeau’s prior distribution of drugs. Evidence of a defendant’s prior drug sales is probative of his intent to distribute, United States v. Harris, 352 F.3d 362, 365 (8th Cir.2003), and intent to distribute was an element of one of the charged offenses. Prior drug distributions also may, in appropriate circumstances, be relevant to proving a defendant’s motive, United States v. Coleman, 284 F.3d 892, 894 (8th Cir.2002), opportunity, cf. United States v. Templeman, 965 F.2d 617, 619 (8th Cir.1992), preparation, Coleman, 284 F.3d at 894, plan, United States v. Haynes, 881 F.2d 586, 590 (8th Cir.1989), knowledge, United States v. Adams, 401 F.3d 886, 894 (8th Cir.2005), and absence of mistake or accident, United States v. Shoffner, 71 F.3d 1429, 1432 (8th Cir.1995). The prior acts to which Big Eagle testified were similar in kind to those for which Drapeau was charged and not overly remote in time: the prior acts were drug distributions that had occurred within the previous three years. (T. Tr. 43, 55). Big Eagle’s testimony was well supported by other evidence; a Task Force agent testified to Drapeau’s admission that he sold drugs to Big Eagle. The jury was instructed that the evidence could be considered only for limited purposes under Rule 404(b), and although Drapeau objected to the admission of the evidence, he did not complain about the specific limiting instruction given to the jury. (Dkt. # 68, Instruction 12; T. Tr. 112-13). We are thus not persuaded that any unfair prejudice outweighed the probative value of the evidence. We discern no abuse of discretion.
C.
Drapeau argues next that the district court erred in excluding evidence of Big Eagle’s kinship to law enforcement personnel. Drapeau maintains that he should have been allowed to impeach Big Eagle’s credibility by introducing evidence that her sister was an employee of the United States Attorney for the District of South Dakota and married to one of the FBI agents working on the Task Force that arrested Drapeau. The district court excluded this evidence, reasoning that it was wasteful of time, confusing to the jury, and irrelevant under Federal Rules of Evidence 402 and 403.
We review the district court’s decision to exclude evidence for abuse of discretion. United States v. Martin, 369 F.3d 1046, 1058 (8th Cir.2004). The Confrontation Clause of the Sixth Amendment guarantees a defendant’s right to cross-examine witnesses and, through cross examination, to expose the motivation of witnesses in testifying. Delaware v. Van Arsdall, 475 U.S. 673, 678-79, 106 S.Ct. 1431, 89 L.Ed.2d 674 (1986). The right to cross-examine witnesses, however, is not without limitation, even where the subject matter is bias. Id. at 679, 106 S.Ct. 1431. Trial judges retain “wide latitude” to impose “reasonable limits on such cross examination based on concerns about, among other things, harassment, prejudice, confusion of the issues, the witness’ safety, or interrogation that is repetitive or only marginally relevant.” Id. The ability of the defendant to .achieve through other means the effect that the excluded examination allegedly would have produced is a factor indicating that his right to confrontation was not violated. See United States v. Warfield, 97 F.3d 1014, 1024 (8th Cir.1996); United States v. Crump, 934 F.2d 947, 952-53 (8th Cir.1991). Limitations on a defendant’s opportunity to impeach a witness for bias, moreover, are subject to harmless error analysis. Van Arsdall, 475 U.S. at 684, 106 S.Ct. 1431.
*876We conclude that the trial court’s decision to disallow Drapeau’s cross-examination of Big Eagle on her family connections to law enforcement, while debatable, was not an abuse of discretion. The court reasoned that Big Eagle’s sister was not in a decision-making position in the U.S. Attorney’s Office, and therefore was powerless to influence any decision regarding Big Eagle’s prosecution. The court also excluded evidence that Big Eagle’s sister was married to an FBI agent involved in Drapeau’s arrest on the basis that the FBI lacked authority to decide whether Big-Eagle would have been prosecuted, and that evidence of an FBI connection would thus be minimally probative of Big Eagle’s bias. The court further believed that discussion of Big Eagle’s brother-in-law would inject into the trial irrelevant issues about Drapeau’s desire to cooperate with the FBI agent rather than police officers assigned to the Task Force. These are judgment calls, and we deem them to be within the range permitted by an abuse of discretion standard of review.
Our conclusion is strengthened by the fact that limitation on Drapeau’s cross-examination of Big Eagle did not preclude Drapeau from challenging her credibility. Drapeau was permitted to cross-examine Big Eagle regarding sources of potential bias and impeachment, including that she was not prosecuted after a seizure of methamphetamine from her car in 2001, that she hoped her cooperation would lead the prosecutor’s office to withhold charges based on that seizure and her admissions of drug activity, and that she continued to use drugs after beginning to cooperate with law enforcement. She also was cross-examined regarding her knowledge of a reward offered by the Crow Creek Sioux Tribe, of which her father was chairman, for information leading to the arrest of drug dealers on the reservation. Dra-peau’s opportunity to cross-examine Big Eagle distinguishes his case from Van Arsdall, where the trial court did not permit the defendant any inquiry into the possibility of bias, 475 U.S. at 679, 106 S.Ct. 1431, and demonstrates that Drapeau was able to achieve much of his desired impeachment through other means. See Warfield, 97 F.3d at 1024.
Even if the district court’s decision to exclude this evidence was an abuse of discretion, we conclude that any error was harmless beyond a reasonable doubt. See Van Arsdall, 475 U.S. at 684, 106 S.Ct. 1431. Whether such an error is harmless depends on “a host of factors,” including “the importance of the witness’ testimony in the prosecution’s case, whether the testimony was cumulative, the presence or absence of evidence corroborating or contradicting the testimony of the witness on material points, and, of course, the overall strength of the prosecution’s case.” Id. While Big Eagle was an important witness, this case involved evidence of a controlled drug transaction, which was recorded on audiotape, and an admission by the defendant that he sold drugs to the informant. Drapeau made use of other avenues to impeach Big Eagle’s testimony. The evidence of guilt was very strong — the district court characterized it as “overwhelming,” (S. Tr. 33-34) — and any incremental impeachment value of the proffered testimony was modest. We are confident that any error was harmless.
D.
Drapeau’s fourth argument is that there was insufficient evidence to support his convictions. When evaluating a challenge to the sufficiency of evidence used by a jury to convict a defendant, we view the evidence “in the light most favorable to the verdict.” United States v. Leisure, 377 F.3d 910, 913 (8th Cir.2004). We draw all reasonable inferences that support the jury’s verdict, and we will over*877turn the verdict “only if no reasonable jury could have found the defendant guilty beyond a reasonable doubt.” Id.
Drapeau maintains that the evidence in his case was insufficient because Big Eagle, the prosecution’s “sole substantive witness,” was so thoroughly impeached that no reasonable jury could have believed her testimony. Drapeau alleges that Big Eagle’s testimony was incredible because she was cooperating with police in the hope of avoiding prosecution for her own drug offenses. Big Eagle’s incentives to cooperate, however, are not sufficient to establish that no reasonable jury could have found her credible. The test for rejecting a jury’s credibility determinations is “extraordinarily stringent.” Crenshaw, 359 F.3d at 988. “Testimony does not become legally unsubstantial because the witness stands to gain by lying; the defendant is entitled to cross-examine such witnesses to expose their motivations, and it is up to the jury to decide whether the witness is telling the truth despite incentives to lie.” Id.
At Drapeau’s trial, Big Eagle’s motivations were explored on cross-examination, and the jury was free to evaluate her credibility in light of information regarding bias and drug use. Her testimony concerning the April 2002 transaction did not “assert[ ] facts that are physically impossible,” Crenshaw, 359 F.3d at 988, and in fact was corroborated by an audio recording and Drapeau’s confession in November that he had sold drugs to Big Eagle on six prior occasions. We therefore hold that the testimony presented to the jury in this case “falls well within the zone of eviden-tiary sufficiency.” Id. at 991.
E.
After the case was submitted, Drapeau filed a pro se document captioned “Supplement Motion to Amend,” in which he argues that the district court lacked jurisdiction over this case, because the statutory jurisdiction provisions of 18 U.S.C. § 1152 do not comply with the “jurisdictional prerequisites of the 1868 Fort Laramie Treaty.” Because this argument potentially implicates our subject matter jurisdiction, we grant the motion and consider Dra-peau’s argument.
Title 18, United States Code, Section 1152 states as follows:
Except as otherwise expressly provided by law, the general laws of the United States as to the punishment of offenses committed in any place within the sole and exclusive jurisdiction of the United States, except the District of Columbia, shall extend to the Indian country.
This section shall not extend to offenses committed by one Indian against the person or property of another Indian, nor to any Indian committing any offense in the Indian country who has been punished by the local law of the tribe, or to any case where, by treaty stipulations, the exclusive jurisdiction over such offenses is or may be secured to the Indian tribes respectively.
We have held that this statute and its exceptions “do not extend or restrict the application of general federal criminal statutes to Indian reservations.” United States v. Blue, 722 F.2d 383, 384 (8th Cir.1983); see also Stone v. United States, 506 F.2d 561, 563 (8th Cir.1974); United States v. White, 508 F.2d 453, 454-55 (8th Cir.1974). Thus, as in Blue, the statute establishes no barrier to the prosecution of a tribal member in federal court for a violation of the federal drug trafficking laws. 722 F.2d at 385.
Drapeau argues that the “jurisdiction of the federal courts under 18 U.S.C. § 1152 and 1153 is valid only if, in a given case, that statutory jurisdiction complies with the jurisdictional prerequisites of the *8781868 Fort Laramie Treaty.” That treaty, between the United States and different bands of the Sioux Nation of Indians, included an article concerning the trial and punishment of tribal members who commit offenses against the United States. See Treaty with the Sioux, Apr. 29, 1868, U.S.Sioux, art. I, 15 Stat. 635. Drapeau draws our attention to the following provision:
If bad men among the Indians shall commit a wrong or depredation upon the persons or property of any one, white, black, or Indian, subject to the authority of the United States, and at peace therewith, the Indians herein named solemnly agree that they will, upon proof made to their agent and notice by him, deliver up the wrong-doer to the United States, to be tried and punished according to its laws.
Id. Drapeau asserts that the issue in this case under the 1868 Treaty is whether federal agents “gave proper and sufficient notice to [the] tribe compelling the tribe under the provisions of the Treaty to ‘deliver up [Appellant] to the United States, to be tried and punished according to its law ....,’ a prerequisite to the implementation of the statutory jurisdictional provisions of sections 1152 and 1153.”
We are not persuaded that the 1868 Treaty deprives the federal courts of jurisdiction over this criminal case. First, the district court’s jurisdiction was not premised on 18 U.S.C. § 1152; as noted, that statute has no effect on the application of general federal criminal statutes, such as the federal drug trafficking statutes. Blue, 722 F.2d at 384. Nor is § 1153 involved in this ease; that statute concerns jurisdiction to prosecute certain enumerated “major crimes” other than drug trafficking. Negonsott v. Samuels, 507 U.S. 99, 102 & n. 2, 113 S.Ct. 1119, 122 L.Ed.2d 457 (1993). The plain language of the treaty, moreover, does not create the sort of “notice” requirement that Drapeau envisions. The treaty does not say that the United States must give notice to an Indian tribe before the government may arrest and prosecute a tribal member who has violated the federal drug trafficking laws. Rather, the treaty imposes an obligation on the tribe to “deliver up the wrong-doer to the United States,” upon proof and notice to the tribe.
Finally, to the extent the treaty could be construed to impose a notice and request obligation on the United States, we have twice approved the opinion in United States v. Consolidated Wounded Knee Cases, 389 F.Supp. 235 (D.Neb.1975), which held that Congress’ grant of citizenship to the Indians, 8 U.S.C. § 1401(a)(2) (now § 1401(b), see Pub.L. No. 95-432, § 3, 92 Stat. 1046 (1978)), makes them “subject to all restrictions to which any other American citizen is subject, in any state,” and that the “legislative history and the language of the statute itself are sufficient expression of a clear Congressional intent to abrogate or modify any treaty provisions to the contrary.” Id. at 243 (internal quotation omitted). See United States v. Kane, 537 F.2d 310, 311 (8th Cir.1976) (per curiam); United States v. Dodge, 538 F.2d 770, 774-76 (8th Cir.1976) (rejecting argument that treaty requires the United States “to request ‘delivery’” from the Tribe of a suspect prosecuted pursuant to § 1153). Drapeau is subject to arrest for violation of the federal drug laws just as is any other American citizen. For these reasons, we reject Drapeau’s pro se challenge to the district court’s jurisdiction.
III.
While this appeal was pending, Drapeau moved for leave to file a supplemental brief on the applicability of Blakely v. Washington, 542 U.S. 296, 124 S.Ct. 2531, 159 L.Ed.2d 403 (2004). We denied *879the motion in anticipation of the Supreme Court’s decision on the constitutionality of the United States Sentencing Guidelines in United States v. Booker, — U.S. -, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005). In Booker, the Court held that the mandatory guidelines were subject to the Sixth Amendment’s requirement 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.” Id. at 756. As a remedy, the Court declared the guidelines effectively advisory in all cases. Id. at 764-65.
At Drapeau’s sentencing, the district court applied the guidelines as mandatory. The court found that Drapeau’s relevant conduct included 1.721 kilograms of drugs, a quantity not found by the jury, and the court applied a two-level adjustment for possession of a dangerous weapon over Drapeau’s objection to the finding of fact. Drapeau objected to his sentence based on Apprendi v. New Jersey, 530 U.S. 466, 120 S.Ct. 2348, 147 L.Ed.2d 435 (2000), arguing that the court’s consider ation of drug quantities beyond those found by the jury and possession of a weapon “constitute[d] an Apprendi violation.” (S. Tr. at 28). Drapeau thus preserved a Sixth Amendment objection, see United States v. Pirani, 406 F.3d 543, 549 (8th Cir.2005) (en banc), and the district court’s application of the mandatory guidelines based on judicial findings concerning drug quantity and possession of a dangerous weapon violated the Sixth Amendment as applied in Booker. We therefore vacate Drapeau’s sentence and remand for resen-tencing. See United States v. Adams, 401 F.3d 886, 900 (8th Cir.2005). Drapeau’s motion for leave to file a supplemental brief in light of Booker is denied as moot.