  In the context of quantum gravity phenomenology, we study the Unruh effect in
the presence of superluminal dispersion relations. In particular, we estimate
the response function and the probability rate for an accelerated detector
coupled to a massless scalar field, whose dispersion relation becomes
essentially quadratic beyond a threshold momentum $k_p$. By means of
perturbative analysis, we show that superluminal dispersion induces a
correction to the Planckian spectrum, which tends to vanish as $k_p$ increases.
