  SIBYLL 2.1 is an event generator for hadron interactions at the highest
energies. It is commonly used to analyze and interpret extensive air shower
measurements. In light of the first detection of PeV neutrinos by the IceCube
collaboration the inclusive fluxes of muons and neutrinos in the atmosphere
have become very important. Predicting these fluxes requires understanding of
the hadronic production of charmed particles since these contribute
significantly to the fluxes at high energy through their prompt decay. We will
present an updated version of SIBYLL that has been tuned to describe LHC data
and extended to include the production of charmed hadrons.
