Jeffrey Allen Larson appeals a magistrate judge’s order dismissing his 28 U.S.C. § 2255 (2000) motion. This court may exercise jurisdiction only over final orders, 28 U.S.C. § 1291 (2000), and certain interlocutory and collateral orders, 28 U.S.C. § 1292 (2000). See Fed.R.Civ.P. 54(b); Cohen v. Beneficial Indus. Loan Corp., 337 U.S. 541, 69 S.Ct. 1221, 93 L.Ed. 1528 (1949). The magistrate judge’s order is neither a final order nor an appealable interlocutory or collateral order. United States v. Bryson, 981 F.2d 720, 723 (4th Cir. 1992) (magistrate judge may hear matters in § 2255 proceedings, but may not decide them absent explicit consent). Moreover, where a dispositive matter is referred to the magistrate judge under 28 U.S.C. § 636(b) (2000), parties must have the opportunity to object, and the district court is required to conduct de novo review of the portions of the recommendation to which objections are made. Bryson, 981 F.2d at 723. Accordingly, we dismiss the appeal for lack of jurisdiction. We dispense with oral argument because the facts and legal contentions are adequately presented in the materials before the court and argument would not aid the decisional process.

DISMISSED