||Despite being computationally more efficient than vector-based approaches, the use of rasterbased techniques for simulating wildfire spread has been limited by the distortions that affect the fire shapes. This work presents a Cellular Automata approach that is able to mitigate this problem with a redefinition of the spread velocity, where the equations generally used in vector-based approaches are modified by means of a number of correction factors. A numerical optimization approach is used to find the optimal values for the correction factors. The results are compared to the ones given by two well-known Cellular Automata simulators. According to this work, the proposed approach provides better results, at a comparable computational cost.