  Plastino and Rocca [Physica A 491, 1023 (2018)] recently criticized our work
[Phys. Lett. A 381, 207 (2017)] on the ground that one should use functional
calculus instead of the ordinary calculus adopted by us in the entropy
maximization procedure. We simply point out that our work requires right from
the beginning $\partial S_q / \partial U = \beta$, whereas the formalism of
Plastino and Rocca yields $\partial S_q/\partial U = q \beta Z^{1-q} \neq
\beta$. Therefore, the work of Plastino and Rocca is irrelevant for our work.
