Hue scale adjustment factors have been determined for CIELAB using the Munsell system. They have been found to vary significantly as a function of hue angle. A formula has been derived based on the 2 degrees observer color-matching functions that models the chroma scale of the Munsell system much more accurately than CIELAB using the same opponent color relationships. In this formula, hue differences can be calculated from hue angle differences, hue scale adjustment factors, and chroma. The hue scale adjustment factors based on hue angle required for the Munsell system have been derived. The variability by hue angle of these factors is such that an analytical hue scale adjustment function as those in CMC or BFD appears insufficient. The adjustment factors are compared to those recently derived by Qiao and coworkers.