  We revisit a class of Z' explanations of the anomalies found by the LHCb
collaboration in $B$ decays, and show that the scenario is tightly constrained
by a combination of constraints: (i) LHC searches for di-muon resonances, (ii)
pertubativity of the Z' couplings; (iii) the $B_s$ mass difference, and (iv)
and electro-weak precision data. Solutions are found by suppressing the Z'
coupling to electrons and to light quarks and/or by allowing for a Z' decay
width into dark matter. We also present a simplified framework where a
TeV-scale Z' gauge boson that couples to standard leptons as well as to new
heavy vector-like leptons, can simultaneously accommodate the LHCb anomalies
and the muon g-2 anomaly.
