A vent integral with the top surface of toner hopper (5) having three labyrinth channels (3a-3c) oriented in one direction and three labyrinth channels (3d-3f) oriented in an orthogonal direction. Each labyrinth communicates with the inside of the hopper by a hole (13a-13f) and the end of each labyrinth communicates with filter pad (7) held in a basin (11) formed in the top surface of hopper (5). Cover (9) closes the vent except for hole (15) over the center of pad (7).