A 3-D instrument self-shading correction has been developed for the MOBY upwelling radiance measurements. This correction was tested using the 23 year time series of MOBY measurements, at the Lanai, Hawaii site. The correction is small (less than 2%) except when the sun and collectors are aligned within 20° azimuth on opposite sides of the main MOBY structure. Estimates of the correction uncertainty were made with a Monte-Carlo method and the variation of the model input parameters at this site. The correction uncertainty was generally less than 1%, but increased to 30% of the correction in the strongest shadow region.