A method for minimizing the intensity of ghost stray light during the optical design process is presented in this paper. Dimensions and, consequently, intensities of ghost images formed in an optical system can be estimated using an analytical algorithm. This algorithm enables construction of a merit function in optical design software, which returns a number proportional to the total intensity of ghost stray light. In this way, an optical system can be simultaneously optimized for the best image quality and for the minimum ghost stray light intensity. The proposed method has been applied to reoptimize a diffraction-limited system of four lenses, and a reduction of ghost stray light by a factor of 6 with almost no degradation of image quality has been achieved.