The invention comprises a hearing aid with a casing and a battery with a battery access door in the casing. According to the invention: the door is hingedly connected to the casing to allow a pivotal motion between the battery door and the casing, a flexible locking latch having a proximal end and a distal end is provided in either casing or battery door, the distal end of the flexible locking latch is arranged to flex along a path in order to release the battery door when an opening force is applied to the door, and an arrest pin is insertable in the moving path of the distal part of the flexible locking latch to block the movement of the latch when a child-resistant battery enclosure is desired.