A novel firearm safety feature includes arresting surfaces for preventing the fall of a hammer in the event of a spontaneous failure of other firearm parts. In a particular embodiment a safety lug has an arresting surface and the hammer has a complementary arresting surface. In the event of a spontaneous failure, the arresting surface and the complementary arresting surface create a positive engagement and prevent the hammer from falling. In another embodiment, a grip safety includes an arresting surface and the hammer includes a complementary arresting surface. In the event of a spontaneous failure, the arresting surface and the complementary arresting surface create a positive engagement and prevent the hammer from falling.