This paper proposes a person tracking framework using a scanning low-resolution thermal infrared (IR) sensor colocated with a wide-angle RGB camera. The low temporal and spatial resolution of the low-cost IR sensor make it unable to track moving people and prone to false detections of stationary people. Thus, IR-only tracking using only this sensor would be quite problematic. We demonstrate that despite the limited capabilities of this low-cost IR sensor, it can be used effectively to correct the errors of a real-time RGB camera-based tracker. We align the signals from the two sensors both spatially (by computing a pixel-to-pixel geometric correspondence between the two modalities) and temporally (by modeling the temporal dynamics of the scanning IR sensor), which enables multi-modal improvements based on judicious application of elementary reasoning. Our combined RGB+IR system improves upon the RGB camera-only tracking by: rejecting false positives, improving segmentation of tracked objects, and correcting false negatives (starting new tracks for people that were missed by the camera-only tracker). Since we combine RGB and thermal information at the level of RGB camera-based tracks, our method is not limited to the particular camera-based tracker that we used in our experiments. Our method could improve the results of any tracker that uses RGB camera input alone. We collect a new dataset and demonstrate the superiority of our method over RGB camera-only tracking.