Abstract: A warning device particularly for use in a coverall worn by a person in a controlled environment warns if the person has unfastened the garment. The garment has fasteners such as a zipper for opening and closing the garment. A pair of electrical contacts are mounted in the zipper track for contact by the zipper head as the zipper head moves along the zipper track. The zipper head establishes continuity through the contacts as it is drawn past. This provides a signal to a transmitter mounted to the coveralls. The transmitter provides a radio frequency signal to a receiver located in a monitoring area. The receiver provides a warning upon reception of the signal.