Selvin Garcia-Garcia pleaded guilty to charges of conspiracy to possess with intent to distribute more than 500 grams of a methamphetamine mixture and possession with intent to distribute more than 50 grams of actual methamphetamine on premises where a child was present or resided. The District Court 1 imposed a *540 sentence of 135 months in prison and 5 years of supervised release. On appeal, Garcia-Garcia’s counsel has filed a brief under Anders v. California, 386 U.S. 738, 87 S.Ct. 1396, 18 L.Ed.2d 493 (1967), arguing that Garcia-Garcia’s guilty plea was involuntary because Garcia-Garcia mistakenly believed that he was eligible for safety-valve relief. Counsel suggests that the interpreter who helped counsel and Garcia-Garcia discuss the plea agreement may not have properly communicated its contents to Garcia-Garcia, who speaks only Spanish. Garcia-Garcia has not filed a pro se supplemental brief.

Garcia-Garcia did not challenge the vol-untariness of his plea in the District Court. His claim is therefore not cognizable in this direct appeal. See United States v. Murphy, 899 F.2d 714, 716 (8th Cir. 1990) (noting that a claim that defendant’s guilty plea was involuntary is not cognizable on direct appeal unless first presented to the district court).

We have reviewed the record independently under Penson v. Ohio, 488 U.S. 75, 80, 109 S.Ct. 346, 102 L.Ed.2d 300 (1988), and we have found no nonfrivolous issues. Accordingly, we affirm.