A jury convicted Richard Toland Fields of conspiracy to possess with intent to distribute fifty grams or more of crack cocaine, in violation of 21 U.S.C. § 846 (2000). The district court sentenced him to a 210-month sentence, which was twenty-five months below the advisory sentencing guideline range. Fields appeals his sentence. We affirm.

Citing United States v. Booker, 543 U.S. 220, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005), Fields contends that his sentence violates the Sixth Amendment. As Fields correctly notes, Booker held that the mandatory application of the federal sentencing guidelines to impose sentencing enhancements based on facts found by the court by a preponderance of the evidence violated the Sixth Amendment. Id. at 233-34, 125 S.Ct. 738. However, the district court treated the guidelines as advisory in determining Fields’ sentence, and the use of the preponderance of the evidence standard while applying the guidelines as advisory does not violate the Sixth Amendment. See United States v. Morris, 429 F.3d 65, 72 (4th Cir. 2005).

Fields also asserts that the district court erred in finding that he was accountable for at least 150 grams of crack and that he possessed a firearm during the course of the conspiracy. Our review of the trial and sentencing transcripts leads us to conclude that the court did not clearly err in making these findings. See United States v. Lamarr, 75 F.3d 964, 972 (4th Cir. 1996) (noting that approximation of amount of drugs for sentencing not clearly erroneous if supported by competent record evidence); United States v. Rusher, 966 F.2d 868, 880 (4th Cir. 1992) (stating standard of review for firearm enhancement).

Accordingly, we affirm Fields’ sentence. We dispense with oral argument because the facts and legal contentions are adequately presented in the materials before the court and argument would not aid the decisional process.

AFFIRMED.