Corey Benjamin appeals after he pled guilty to a firearm offense, in violation of 18 U.S.C. §§ 922(g)(1), 924(a)(2), and 924(e), and the district court 1 sentenced him to fifteen years in prison, the statutory minimum. His counsel has filed a brief under Anders v. California, 386 U.S. 738, 87 S.Ct. 1396, 18 L.Ed.2d 493 (1967), requesting leave to withdraw.

Benjamin’s own admissions at his change-of-plea hearing established that he had violated 18 U.S.C. § 922(g)(1), and that he had at least three previous convictions for separate offenses within the terms of 18 U.S.C. § 924(e). Thus, after carefully and independently reviewing the record in accordance with Penson v. Ohio, 488 U.S. 75, 109 S.Ct. 346, 102 L.Ed.2d 300 (1988), we conclude that there are no non-frivolous issues for review. See 18 U.S.C. § 924(e) (person who violates § 922(g)(1) and has three previous convictions for violent felony or serious drug offense, or both, committed on different occasions from one another, shall be imprisoned not less than 15 years); United States v. Watts, 553 F.3d 603, 604 (8th Cir. 2009) (per curiam) (“District courts lack the authority to reduce sentences below congres-sionally-mandated statutory mínimums.”) (citation omitted).

*665 Accordingly, we grant counsel’s motion to withdraw, and we affirm.