Oscar Lee directly appeals after he pleaded guilty to a firearm charge under 18 U.S.C. § 922(g) and the district court 1 sentenced him as an armed career criminal to fifteen years in prison, the mandatory minimum under 18 U.S.C. § 924(e). His counsel has moved to withdraw and filed a brief under Anders v. California, 386 U.S. 738, 87 S.Ct. 1396, 18 L.Ed.2d 493 (1967), challenging the reasonableness of Lee’s sentence.

Upon careful review, we conclude that the district court properly determined that Lee qualified as an armed career criminal. See 18 U.S.C. § 924(e); see also United States v. Rodriguez, 612 F.3d 1049, 1056-57 (8th Cir. 2010) (rejecting challenge to sentence based on age of § 924(e) predicate offenses). We also note that the district court had no authority to impose a prison term of fewer than the statutory minimum term of fifteen years. See United States v. Watts, 553 F.3d 603, 604 (8th Cir. 2009) (per curiam).

Having independently reviewed the record under Penson v. Ohio, 488 U.S. 75, 109 S.Ct. 346, 102 L.Ed.2d 300 (1988), we find no nonfrivolous issues. Accordingly, we affirm the judgment of the district court, and we grant counsel’s motion to withdraw.