Abstract: There is provided a lock system for securing a printer door to prevent theft of an ink cartridge. The lock system comprises a lock housing that is attachable adjacent the printer door and which has a lateral aperture extending generally parallel thereto. The lock system further comprises a locking member disposed within the lateral aperture and which is slidable therealong between unlock and lock positions. Its locking portion becomes substantially retracted within the lateral aperture when in the unlock position. The locking portion becomes extended over the printer door when in the lock position to secure the same and prevent theft of the ink cartridge thereby.