Evolutionary-mass estimates from bonnsai (M_ev(B)) vs. spectroscopic masses (M_sp). Grey open symbols: possible single-lined spectroscopic binaries (Sana et al. 2013; Walborn et al. 2014), stars with poor fits to He lines, high gravities (log g > 4.2) or low helium abundance, and objects with possible or confirmed fibre contamination. Filled grey symbols: objects from HHeN analysis and no indications of binarity or fibre contamination. Red symbols: rest of the sample. The dashed grey line indicates the one-to-one relation, with ±25 and ±50% shown by the dotted lines. Typical error bars are given in the upper left corner. O2 stars were excluded.