A unit for use with a removable toner cartridge of an image forming device according to one example embodiment includes a housing having a reservoir for holding toner. An inlet port is positioned to receive toner from the toner cartridge. The inlet port is connected to the reservoir to allow the toner received from the toner cartridge to enter the reservoir. A shutter is slidably movable between a closed position and an open position. A biasing member biases the shutter toward the closed position. The shutter includes a first engagement surface positioned to receive a first engagement member of the toner cartridge to begin to open the shutter as the toner cartridge is inserted in the image forming device. The shutter also includes a second engagement surface positioned to receive a second engagement member of the toner cartridge to move the shutter a remaining distance to the open position.