In an earlier paper (Hildenbrand, D. L.; Lau, K. H.; Chandra, D. J. Phys. Chem. B 2010, 114, 330.), we detected the presence of NH4NO3(g) in the vapor over the solid nitrate and evaluated its partial pressure along with those of HNO3 and NH3. The molecular constants of the gaseous nitrate were estimated in the absence of experimental values in an attempt to derive its enthalpies of sublimation and formation. After publication, we became aware of the sought molecular data, evaluated primarily from high-level theoretical calculations, and revised the analysis to yield Delta H-f(298)o(NH4NO3(g)) = -61.8 +/- 5 kcal mol(-1).