Lucas van der Merwe appeals the district court’s 1 order denying his motion to dismiss his Medicare overpayment debt. The district court’s order is not appealable, as the order is not a final decision and there is no basis to apply the collateral-order doctrine. See 28 U.S.C. § 1291 (courts of appeals have jurisdiction of appeals from final decisions of district courts); Alpine Glass, Inc. v. Country Mut. Ins. Co., 686 F.3d 874, 877 (8th Cir. 2012) (district court’s order is final if it ends litigation on merits and leaves nothing more for court to do but execute judgment); Langford v. Norris, 614 F.3d 445, 454-56 (8th Cir. 2010) (interlocutory appeals are exceptional; under collateral-order doctrine, otherwise non-final order is immediately appealable only if it is conclusive, resolves important questions separate from merits, and is effectively unreviewable on appeal from final judgment). Accordingly, we dismiss the appeal for lack of jurisdiction.