A temporary closure with a solid pane of for example glass framed in a quadrangular frame that includes four side members forming at least a part of each their side of the frame sides; eight corner members each telescopically connected to a side member and in pairs forming the four corners of the frame; four longitudinal mountings fastened on each their side member and each arranged to displaceably receive an area of the pane, and a fastener for fixing the pane in a wanted position in the frame. The frame includes at least one corner plate fastened on each of the corners of the frame and having sides that are longer than the extent of the adjacent mounting in the transverse direction. The temporary closure can be mounted and demounted quickly and easily, and its size can be changed to adapt to an opening. The temporary closure gives good security against the intrusion of unauthorized persons, as the solid pane cannot easily be broken through or cut open in the same way as panes consisting of a flexible plastic sheet.