A fuel injector includes an upper housing having an outer peripheral surface; a nozzle tip with a nozzle opening which serves as an outlet to fuel from the fuel injector; and a valve needle which is selectively moveable between a first position which prevents fuel flow and a second position which permits fuel flow. The fuel injector also includes an inlet sleeve which includes an inner peripheral surface which circumferentially surrounds, and mates with, the outer peripheral surface of the upper housing. The inlet sleeve is fixed to the upper housing, thereby preventing relative movement between the inlet sleeve and the upper housing. The inlet sleeve includes external threads which are configured to mate with complementary internal threads of a nut which secures a fuel supply conduit to the upper housing.