In a film wrapping machine for wrapping packages in stretchable film, a monitoring system is provided to generate a signal each time film is drawn into the machine. If no film is drawn into the machine indicating that the film source has expired, broken or otherwise become disengaged from the film feeding apparatus for the wrapping machine, the machine is stopped. The film draw into the machine is monitored by an electrical switch which is coupled to a tensioning roller, the motion of which is adjusted to activate the switch each time even at least a minimum length of film is drawn into the machine.