Under the assumption of chemical homogeneity, the Arches cluster stars display a pronounced Γ-dependence. Squares indicate stars with spectral subtypes WNh (filled blue: H-deficient; unfilled: normal H abundance), and circles O/Of. The black dashed line indicates the fitted mass-loss relation (Eq. (14)) for WNh stars (parameters from Table 2 row 2). The red dotted line indicates the corresponding fit for the complete sample (parameters from Table 3 row 2).