A toner cartridge according to one example embodiment includes a housing having a toner reservoir. An outlet port faces downward on a front of the housing near a first side of the housing. A shutter is movable between a closed position blocking the outlet port and an open position unblocking the outlet port. A flag on the first side of the housing is movable between a first position and a second position. The flag extends outward sideways from the first side when the flag is in the second position. The flag is operatively connected to the shutter such that when the shutter moves from the closed position to the open position the flag moves from the first position to the second position to change a state of a sensor in the image forming device when the toner cartridge is installed in the image forming device.