A fuel overflow prevention device for minimizing or eliminating fuel spillage during fuel storage container filling. The device may also minimize or eliminate some types of fuel spillage after filling. The device includes an overflow prevention chamber for receiving therein fluid from a fuel storage container vent tube. The overflow prevention chamber also includes a space for removably receiving and retaining therein the spout of an automatic shutoff fuel nozzle including a sensor port. A flow restriction interface is established between an interior portion of the overflow prevention chamber and the exit port of the spout. Fluid received from the vent tube into the overflow prevention chamber fills the space until covering the sensor port to a level sufficient to trigger automatic nozzle shutoff. The device optionally includes a vent tube extension to aid in regulating the fuel level within the container at which nozzle shutoff is triggered.