A firearm has a magazine disconnect mechanism. The firearm includes a trigger operable between a resting position and a pulled position. The magazine disconnect mechanism has a trigger block positioned between the trigger and a magazine well of the firearm, where the trigger block is movable between a blocking position and a non-blocking position. In the blocking position the trigger block obstructs moving the trigger to the pulled position. The trigger block occupies the non-blocking position when a magazine is installed in the magazine well, and the trigger block occupies the blocking position when the magazine is absent from the magazine well.