  In this paper we have consider the thermodynamics of a photon gas subject to
the presence of a minimal measurable length following from a covariant
extension of the original generalized uncertainty principle (GUP). After
establishing consistently a generalized dynamics, we define a GUP deformed
Maxwell invariant which serves as the basis for our study. In order to
highlight the GUP effects we compute the one- and two-loop order contribution
to the partition function at the high-temperature limit. Afterwards, by
computing the internal energy density we conclude that the additional terms can
be seen as corrections $\delta\sigma_{\rm{gup}}$ to the Stefan-Boltzmann law
due to GUP effects.
