Abstract: The invention relates to an add-on for a spirit level, designed as a marking aid for indicating and as a marking instrument for marking the position of drilled holes for mounting objects on a wall, wherein the add-on is fastened releasably on a spirit level and is arranged to be movable along the longitudinal axis of this spirit level. The object of the invention is that an add-on of this kind be designed in such a way that, during alignment, a spirit level equipped with this add-on bears fully on the associated wall and that the elements of the add-on that are necessary for a marking come into operational contact with the wall only temporarily. This object is achieved by the fact that the add-on has a pin head, a double U-shaped middle part and a fastening part for connection to the spirit level, with specific designs being proposed for these assemblies.