  We investigate persistent currents in metallic rings interrupted by a Coulomb
blockaded topological superconducting segment. We show that the presence of
Majorana bound states in the superconductor is reflected in the emergence of an
h/e harmonics in the persistent current, whose sign is determined by the
fermion parity of the superconductor. The Majorana bound states further render
the current finite at zero flux, nevertheless the resulting peculiar symmetry
of the persistent current is compatible with a free energy that is even in
time-reversal symmetry breaking fields. These unique features of the persistent
currents are robust against disorder and provide unambiguous signatures of the
presence of Majorana fermions.
