Abstract: A safety device for cooperation with the internal safety mechanism of a firearm to provide an audible signal to the shooter when the safety is off and the weapon is ready to fire. A main body member located adjacent the firearm trigger guard at the location of the conventional safety defines a chamber within which an alarm system is housed including a power source as well as signal generating means. A switch closing member is disposed so as to contact the trigger guard when the safety is off to close a signal generating circuit of the alarm. The alarm system is of modular construction for removable disposition within the main body chamber.