The invention relates to a fuel injector having a solenoid valve for actuating an armature assembly which is configured in one piece or a plurality of pieces. A closing element is actuated via this in order to relieve the pressure in a control chamber. The armature assembly is guided in an armature guide which is fastened in the injector body by means of a valve-clamping screw. In a fixing region in the injector body, the armature guide has at least one circumferential recess which allows for deformation of the fixing region during fastening by the valve-clamping screw.