This note reports improved energy resolution measured using a gamma-ray detector consisting of a 2 mm×2 mm×4 mm long CsI(Tl) scintillator coupled to a 2 mm×2 mm photodiode. Energy resolution of 7.5&percent; full width at half-maximum (FWHM) was obtained for the 122 keV photopeak of Co-57. Energy resolution of 35&percent; FWHM was obtained for the 5.9 keV photopeak of Fe-55. ©1997 American Institute of Physics.