We revisit a class of Z 0 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 dimuon resonances, (ii) perturbativity of the Z 0 couplings; (iii) the B s mass difference, and (iv) electroweak precision data. Solutions are found by suppressing the Z 0 coupling to electrons and to light quarks and/or by allowing for a Z 0 decay width into dark matter. We also present a simplified framework where a TeV-scale Z 0 gauge boson that couples to standard leptons as well as to new heavy vectorlike leptons, can simultaneously accommodate the LHCb anomalies and the muon g − 2 anomaly.