A jury found Jozabet Castro-Garzon guilty of conspiracy to distribute 500 grams or more of methamphetamine in violation of 21 U.S.C. § 846. At sentencing, the district court 1 found Castro-Garzon accountable for fifteen kilograms or more of methamphetamine. It thus sentenced him to 188 months, a five-year term of supervised released, and ordered him to pay a $100 special assessment. CastroGarzon’s sole contention on appeal is the district court violated his Sixth Amendment right to jury trial by refusing to have the jury determine the quantity of methamphetamine involved in the conspiracy.

Castro-Garzon’s claim is without merit. Under an advisory guidelines system, the court’s determination of drug quantity for sentencing purposes by a preponderance of the evidence does not violate the Sixth Amendment. See, e.g., United States v. Tabor, 439 F.3d 826, 830 (8th Cir. 2006). Therefore, we affirm.