The ionic Hall effect has been measured in the crystalline fast ion conductor rubidium silver iodide, RbAg4I5, at temperatures from 373 K to 473 K. A novel variant of the alternating E/alternating B technique has been employed, with the alternating magnetic field supplied by a rotating permanent I T magnet. The value of the Hall mobility is found to be considerably smaller than reported earlier by T. Kaneda and E. Mizuki. It is now found to be identical with the drift mobility obtained under the assumption that all the silver ions in the solid electrolyte contribute to the conduction process. The same is known to hold in the archetypal fast ion conductor alpha-AgI.