A locking system for mechanical joining of floorboards including horizontal joining of a first and a second joint edge portion of a first and a second floorboard respectively at a vertical joint plane and vertical joining of the first and second joint edge portions, the tongue, the tongue groove, the locking element and the locking groove have a configuration that allows insertion of the locking element into the locking groove by inward angling of the second floorboard towards the first floorboard while maintaining contact between the joint edge portions, and the tongue, the tongue grove, the locking element and the locking groove have a configuration that allows insertion of the locking element into the locking groove by a substantially vertical snap action.