Some factors (long etching and annealing effects) are experimentally and theoretically studied, neglect of which has resulted in low ages in the fission track datings of geological samples. The empirical correction methods, proposed by Storzer and Wagner concerning these factors, are reinvestigated. It is shown that these corrections can also be calculated theoretically. The problem is considered in fuller details for glass samples. A new method is proposed for the correction of the thermally reduced fission-track ages of glasses.