© 2017, The Author(s). We determine the charm quark mass m^ c from QCD sum rules of the moments of the vector current correlator calculated in perturbative QCD at O(α^s3). Only experimental data for the charm resonances below the continuum threshold are needed in our approach, while the continuum contribution is determined by requiring self-consistency between various sum rules, including the one for the zeroth moment. Existing data from the continuum region can then be used to bound the theoretic uncertainty. Our result is m^ c(m^ c) = 1272 ± 8 MeV for α^ s(MZ) = 0.1182 , where the central value is in very good agreement with other recent determinations based on the relativistic sum rule approach. On the other hand, there is considerably less agreement regarding the theory dominated uncertainty and we pay special attention to the question how to quantify and justify it.