An accelerator mixture for peroxide hardeners, in particular an accelerator mixture for an organic peroxide-curing resin mixture, a two-component mortar system containing the same for chemical fastening and use of the same for chemical fastening of anchoring means in boreholes are described. Using a mixture of bis-N-substituted p-toluidines with bis-N substituted anilines or bis-N-substituted m-toluidines, it is possible to provide a mortar composition for chemical fastening of anchoring elements in boreholes, which will have an improved low-temperature curing and improved load ratings at high temperatures with an extended gel time.