Abstract: A modified pin to be used in an existing tumbler and pin lock to prevent the lock from unauthorized operation by a lock-picking technique known as “bumping.” A modified replacement pin is provided for an existing pin and tumbler lock. This modified replacement pin fits within the rotatable plug in the pin and tumbler lock. It replaces one of the longer pins of an existing pin set. The existing pin is cylindrical in shape. To modify the pin, a symmetrical notch is cut in proximity to one end of the pin. This notch causes the modified pin to catch on the plug during an attempted unauthorized opening by bumping the lock. Because the notch catches on the plug, it prevents the plug from turning. This effect is momentary but is enough to allow remaining pins in the pin and tumbler lock to fall into place to prevent the plug from turning and unauthorized operation of the lock.