The invention relates to a fixing thread (1, 5, 10, 16) for stitching reinforcing fibres, in particular, for forming a fibre preform in order to produce a composite fibre-reinforced component by impregnating with a hardenable plastic material. The inventive fixing thread (1, 5, 10, 16) comprises an interface (4, 9, 15, 19) for locally increasing the ductility of a matrix made of said hardenable plastic material and at least one base thread (2, 6, 11, 12,17) in particular for reducing the formation of almost obligatory microcracks in the matrix of a finished composite component in the puncture areas of the fixing thread (1, 5,10,16). Said interface can be, for example formed by applying a coating covering the base thread (1) with the aid of a thermoplastic material, such as polyethylene, polypropylene or the like.