  We present our analysis aimed at inferring average magnetic fields in
slowly-rotating solar-like stars. Using the spectral line inversion code
SPINOR, we perform high-accuracy line profile fitting and investigate whether
Zeeman broadening can be reliably detected in optical data of unprecedented
quality. We argue that our usage of both high- and low-g_{eff} lines does
provide a certain sensitivity to magnetic fields that may, indeed, be detected.
However, the measurement is subject to a model dependence and prone to
ambiguities, e.g. due to spectral blends. Hence, while a field may be
successfully recovered, the quantification of this field is subject to large
uncertainties, even for the highest-quality optical data.
