Electric dipole moments (EDM) of non-degenerate systems with angular momentum violate parity and time
symmetry, and by the virtue of the CPT-theorem also the combined symmetry of charge and parity (CP).
Although CP violation (CPV) is an established ingredient of the weak sector of the standard model of
particle physics (SM), its contribution to an EDM of a fundamental particle is too small to be measured any
time soon. Therefore, any discovery of an EDM would be a genuine signal of yet unobserved physics. As
the muon is the only accessible probe of the second generation of fermions and the only fermion of which
the EDM can be measured on the bare particle, a search for a muon EDM thus uniquely complements more
established searches using atoms and neutrons. Here we report on the status of a search for the muon EDM
using the frozen-spin technique in a compact storage ring, aiming for an improvement by three orders of
magnitude in sensitivity compared to the current best direct limit d_mu ≤ 1.8 × 10−19 e·cm.