A fastener driver includes a housing, a cylinder disposed within the housing, a piston positioned and movable within the cylinder, a driver blade attached to the piston and movable with the piston, a motor for driving movement of the piston, a battery removably coupled to the housing for supplying power tot the motor, a nosepiece at least partially defining a fastener driving track through which fasteners are driven by the driver blade, and a magazine operable to supply the fasteners to the nosepiece. The magazine is removable from the nosepiece only in response to prior removal of the battery from the housing.