  Automated tools for the computation of amplitudes and cross sections have
become the backbone of phenomenological studies beyond the standard model. We
present the latest developments in MadDM, a calculator of dark-matter
observables based on MadGraph5_aMC@NLO. The new version enables the fully
automated computation of loop-induced annihilation processes, relevant for
indirect detection of dark matter. Of particular interest is the direct
annihilation into photons, $\gamma \gamma,\, \gamma X$. These processes lead to
monochromatic gamma-ray lines that are smoking-gun signatures for dark-matter
annihilation in our Galaxy. MadDM computes the predictions for the expected
photon fluxes near Earth and derives constraints from the gamma-ray line
searches by Fermi-LAT and HESS. As an application, we present the implications
for the parameter space of the Inert Doublet Model.
