In some recent studies [1]–[3], Aman et al. used the Ruppeiner scalar as a measure of underlying interactions of Reissner-Nordström black holes, indicating that it is a non-interacting statistical system for which classical thermodynamics could be used at any scale. Here, we show that if we use the complete set of thermodynamic variables, a non-flat state space will be produced. Furthermore, the Ruppeiner curvature diverges at extremal limits, as it would for other types of black holes.