Results from Møller et al. (2013) with the high-redshift measurement of GRB 130606A included. [M/H]_{100 km s^-1} is the metallicity expected for DLAs with ΔV = 100 km s^-1, based on the overall mass-metallicity relation. The data of Møller et al. (2013; filled circles) favour a break in the evolution of the mass-metallicity relation at z ~ 2.6 (dashed line), which is also supported by our measurement of GRB 130606A (filled square). We assumed for this point ΔV = 90 km s^-1 and [ M/H ] = −1.3 ± 0.2; see text.