This invention is for improvements in or relating to mine roof supports of the kind (hereinafter referred to as the kind specified) comprising a base structure, one or more hydraulically extensible props or legs mounted on said base structure and a roof-engaging structure mounted on said props or legs for application thereby to the roof to be supported. Generally the roof-engaging structure is at least in part in the form of a canopy. When a row of such supports is assembled at a mineral face a walkway is provided, under said canopy, along which miners can travel in comparative safety. To enable the supports to be advanced towards the mineral face, as winning of mineral therefrom proceeds, it is necessary that there should be some clearance or space or freedom for movement between the roof-engaging structures or canopies of neighboring roof supports. There is a risk, therefore, of miners being injured by mineral falling through said clearance or space. One object of the present invention is to provide improved means for avoiding this and which at the same time will not interfere with the advancing of a support.