Jo Ann Hoffmann appeals the district *529 court’s 1 dismissal of her Federal Tort Claims Act (FTCA) action for failure to serve the defendant. We grant her leave to appeal in forma pauperis, and we affirm the dismissal, modifying it to be without prejudice.

We conclude that the district court did not abuse its discretion in dismissing Hoffmann’s action for insufficient service. See Bullock v. United States, 160 F.3d 441, 442 (8th Cir. 1998) (per curiam) (standard of review). In an FTCA action, the United States is the real defendant. See 28 U.S.C. § 2679. To serve the United States properly, Hoffmann had to deliver a copy of the summons and complaint to the U.S. Attorney’s Office for the district in which the action was brought, as well as to the Attorney General of the United States. See Fed.R.Civ.P. 4(i). Hoffman served neither. Because more than 120 days had passed between the filing of the complaint and the dismissal, the district court could dismiss the action sua sponte; however, the dismissal should have been without prejudice. See Fed.R.Civ.P. 4(m) (where service is not timely made, “court ... shall dismiss the action without prejudice”).

The judgment is affirmed, but the dismissal is modified to be without prejudice.