In this work we consider a mobile robot with a laser range finder. Our goal is to find the best set of lines from the sequence of points given by a laser scan. We propose a probabilistic method to deal with noisy laser scans, in which the noise is not properly modeled using a Gaussian Distribution. An experimental comparison with a very well known method (SMSM), using a mobile robot simulator and a real mobile robot, shows the robustness of the new method. The new method is also fast enough to be used in real time.