Pedro Damian Martinez-Carrillo (“Martinez”) appeals his guilty-plea conviction and sentence for possession of more than 100 kilograms of marijuana with intent to distribute, a violation of 21 U.S.C. § 841(a)(1) and (b)(1).

Martinez argues that the district court improperly assessed criminal-history points under the Sentencing Guidelines for his two prior uncounseled federal convictions of illegal entry, for which he was sentenced to terms of stand-alone probation. He contends that use of these uncounseled convictions was prohibited by Alabama v. Shelton, 535 U.S. 654, 122 S.Ct. 1764, 152 L.Ed.2d 888 (2002). As Martinez acknowledges, this argument is foreclosed by United States v. Perez-Macias, 335 F.3d 421, 427-28 (5th Cir. 2003). He raises the argument only to preserve it for possible further review.

Martinez also maintains that the sentencing scheme of 21 U.S.C. § 841 is facially unconstitutional in light of Apprendi v. New Jersey, 530 U.S. 466, 490, 120 S.Ct. 2348, 147 L.Ed.2d 435 (2000). As Mar *960 tinez concedes, his argument is foreclosed by this court’s decision in United States v. Slaughter, 238 F.3d 580, 582 (5th Cir. 2000). He raises the issue only to preserve it for possible further review.

The judgment of the district court is AFFIRMED.