RONALD LEE GILMAN, Circuit Judge. Defendants Wendell Brown and Gary T. Reed were convicted of conspiring to distribute and possess with the intent to distribute at least 50 grams of methamphetamine (meth), in violation of 21 U.S.C. §§ 846, 841(a)(1), and 841(b)(1)(A). Both defendants appeal their convictions, arguing that the district court erred by failing to give a “buyer-seller instruction” to the jury. They also appeal their sentences, arguing that the district court committed a procedural error when calculating their Guidelines ranges under the United States Sentencing Guidelines (the Guidelines). Brown separately contends that his conviction should be overturned because the district court erroneously admitted an incriminating statement by Reed, his nontestifying codefendant. For the reasons set forth below, we AFFIRM Brown’s and Reed’s convictions, but VACATE their sentences and REMAND to the district court for further proceedings consistent with this opinion.