A secondary securing means for locking an electrical plug connection of a first electrical plug connector and a mating plug connector includes a securing element and a plug-in prevention means. By a closing movement, the securing element can be moved from a preliminary latching position into a locking position in which the securing element mechanically secures the plugged plug connection. The securing element is operatively connected to the plugging prevention means in such a way that, during the closing movement of the securing element, the plug-in prevention means can be moved from a home position in which the plugging prevention means blocks a complete insertion of the mating plug connector into the first plug connector, to a clearing position in which the plug-in prevention means clears the displacement path between the mating plug connector and the first plug connector complete insertion of the mating plug connector into the first plug connector The plug-in prevention means moving from the home position into the clearing position by rotation about an axis of rotation or along a support element.