  Planck spectrum of black body radiation is usually derived by considering of
quantized free electromagnetic field at a finite temperature. The
minimum-length deformed quantization affects field theory both at the first and
second quantization levels. Performing an exact calculation to the first order
in deformation parameter, both of the corrections turn out to be of the same
order. Nevertheless, the correction at the second quantization level has some
qualitative difference, that may be interesting for future study to
differentiate between these two sorts of corrections. In itself the correction
to the black body radiation seems to be innocuous in light of the big-bang
nucleosynthesis whenever the minimum length is less or equal to $10^{-19}$cm.
