  Several years ago, it has been discussed that non-logarithmic entropies such
as the Tsallis q-entropy cannot be applied to systems with continuous
variables. Now, in their recent paper [Phys. Rev. E 97, 012104 (2018)],
Oikonomou and Bagci have modified the form of the q-entropy for discrete
variables in such a way that its continuum limit exists. Here, it is shown that
this modification violates the expandability property of entropy, and their
work is actually a supporting evidence for the absence of the q-entropy for
systems with continuous variables.
