Seismic masses for a sample of halo and thick-disk stars as a function of stellar metallicity. The open grey symbols show the original values taken from Epstein et al. (2014). Black symbols correspond to masses from the classical scaling relations as done by Epstein et al. (2014), but based on Δν_c determined from the full Kepler data sets. Coloured symbols show the masses based on our re-calibrated scaling relations, where the colour indicates the observed large frequency separation Δν_c. The grey-shaded bars indicate the expected mass based on the high age and low metallicity constraints for these stars (Epstein et al. 2014).