Raul Madraso pleaded guilty to possessing more than 50 grams of crack with intent to distribute; his 1995 felony drug conviction increased his mandatory minimum prison term to 20 years. See 21 U.S.C. §§ 841(a)(1), (b)(1)(A), 851. The district court 1 sentenced Madraso to 240 months in prison and 10 years of supervised release. On appeal, 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). For the following reasons, we affirm.

First, Madraso’s sentence is not unreasonable: 240 months was the statutory minimum, and the district court had no authority to depart or vary downward because the government did not move for a lower sentence based on substantial assistance and Madraso did not qualify for safety-valve relief. See 18 U.S.C. § 3553(e), (f); United States v. Gregg, 451 F.3d 930, 937 (8th Cir. 2006); United States v. Chacon, 330 F.3d 1065, 1066 (8th Cir. 2003). Second, Madraso’s prior felony conviction was properly used to enhance his sentence. See United States v. Thomas, 930 F.2d 12, 14 (8th Cir. 1991) (no Double Jeopardy Clause violation). Third, it was within the government’s discretion to file the sen *912 tence-enhancing section 851 information, absent any allegation that the decision was based on an improper factor. See United States v. LaBonte, 520 U.S. 751, 761-62, 117 S.Ct. 1673, 137 L.Ed.2d 1001 (1997). Finally, after reviewing the record independently under Benson v. Ohio, 488 U.S. 75, 80, 109 S.Ct. 346, 102 L.Ed.2d 300 (1988), we find no nonfrivolous issues.

Accordingly, we grant counsel leave to withdraw, and we affirm the judgment.