  Gamma-rays are, with antiprotons, a very efficient way to derive upper limits
on the density of evaporating black holes. They have been successfully used in
the last decades to severely constrain the amount of Primordial Black Holes
(PBHs) in our Universe. This article suggests a little refinement, based on the
expected background, to improve this limit by a factor of three. The resulting
value is : Omega_PBH < 3.3E-9.
