After pleading guilty to being a felon in possession of a firearm, Carlton Samuels appeals the district court’s 1 within-Guidelines sentence. 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 the district court erred by imposing an unreasonable sentence, and that Samuels received ineffective assistance of counsel when counsel failed to object to the 4-level enhancement for using or possessing the firearm in connection with another felony offense. .Samuels has filed a motion making the same ineffective-assistance argument and a letter arguing that police did not have a proper search warrant when they discovered the firearm.

We conclude that the sentence was not substantively unreasonable. A sentence within the advisory guideline range is presumed reasonable, see United States v. Callaway, 762 F.3d 754, 760 (8th Cir. 2014), and the court imposed the sentence after considering the 18 U.S.C. § 3553(a) factors, see United States v. Miller, 557 F.3d 910, 917 (8th Cir. 2009). To the extent Samuels is attempting to assert a Fourth Amendment claim on appeal, his valid guilty plea waived such a claim. See United States v. Arrellano, 213 F.3d 427, 430 (8th Cir. 2000). The district court’s application of a four-level increase under USSG § 2K2.1(b)(6)(B) was supported by the evidence. We deny the ineffective-assistance claim, as such claims are best litigated in collateral proceedings. See United States v. Ramirez-Hernandez, 449 F.3d 824, 826-27 (8th Cir. 2006). Having independently reviewed the record pursuant to Penson v. Ohio, 488 U.S. 75, 109 S.Ct. 346, 102 L.Ed.2d 300 (1988), we find no non-frivolous issues for appeal.

Accordingly, we affirm the district court, grant counsel’s motion to withdraw, and deny Samuels’s motion.