A firearm has a frame, a slide, a striker-type firing pin ("striker"), and a fire control mechanism including a sear to controllably release the striker and a trigger bar for actuating the sear. An automatic positive striker lock safety includes a pin-like safety element biased downwards to normally block the striker. The bottom of the pin is rounded, and cooperates with a rearwards facing, sloped surface on the trigger bar. If striker becomes free to move forward without full rearwards movement of the trigger bar, the pin blocks the striker. However, rearward movement of the trigger bar forces the pin upwards. As the trigger bar reaches its fully rearward position, the pin is moved to unblock the striker, and the sear is actuated for releasing the striker.