An overhead door safety system includes a loading dock having a loading dock wall defining an opening. A truck and trailer door safety device is mounted to the loading dock wall. The truck and trailer door safety device includes a mounting bracket adapted for mounting to the loading dock wall and a swing arm. The swing arm includes an arm extension portion and a pivot portion. The pivot portion is pivotally mounted to the mounting bracket so that the swing arm pivots about a pivot axis between a retaining position and a storage position. In the retaining position, the arm extension portion is disposed beneath an overhead door of a truck positioned adjacent to the opening of the loading dock wall to prevent the overhead door from closing.