The fastening device 10 of FIG. 3 is provided for fastening a flexible material to a structure. The fastening device 10 comprises an elongate fastening member 12 having a male portion 11 and a base portion 13. The base portion 13 provides a plurality of indentations 14 at spaced apart intervals along the length of the fastening member 12. The indentations 16 are adapted for securing the fastening member 12 to the structure with the use of fasteners extending through the indentations 16. The male portion 11 is shaped for receiving an elongate clip-type retaining member 24. The male portion 11 provides a channel 15 on its surface facing away from the base portion 13 for cooperating with a projection 17 on an inner surface of the clip-type retaining member 24. The channel 15 is positioned for alignment with the projection 17 for receiving the flexible material as the projection 17 forces the flexible material into the channel 15. The fastening system allows for easy replacement of damaged or worn shade cloth, and allows for re-use of the existing fastening system for positioning of new shade cloth.