  Quantum phase slips are traditionally considered in diffusive superconducting
wires which are assumed homogeneous. We present a definite estimate for the
amplitude of phase slips that occur at a weak inhomogeneity in the wire where
local resistivity is slightly increased. We model such a weak link as a general
coherent conductor and show that the amplitude is dominated by topological part
of the action. We argue that such weak links occur naturally in apparently
homogeneous wires and adjust the estimate to that case. The fabrication of an
artificial weak link would localize phase slips and facilitate a better control
of the phase-slip amplitude.
