Pedro Omar Velazquez Martinez (Martinez) appeals the 120-month statutory minimum prison sentence the district court1 imposed after he pleaded guilty to one count of conspiracy to distribute 500 grams or more of methamphetamine, in violation of 21 U.S.C. §§ 846 and 841(b)(1)(A), and two counts of possession with intent to distribute 500 grams or more of methamphetamine, in violation of 21 U.S.C. § 841(a)(1), (b)(1)(B). His counsel has moved to withdraw and has filed a brief under Anders v. California, 386 U.S. 738, 87 S.Ct. 1396, 18 L.Ed.2d 493 (1967), arguing that Martinez’s plea was involuntary because he pleaded guilty under the mistaken impression that he could qualify for safety-valve relief. This argument is not properly before us. See United States v. Murphy, 899 F.2d 714, 716 (8th Cir.1990) (claim of involuntary guilty plea must first be presented to district court, and is not cognizable on direct appeal). Further, having reviewed the record independently under Penson v. Ohio, 488 U.S. 75, 109 S.Ct. 346, 102 L.Ed.2d 300 (1988), we have found no nonfrivolous issues for appeal.
Accordingly, we affirm the district court’s judgment.