Unclumped wind momentum versus luminosity for the combined sample from this work and Mokiem et al. (2007). The different symbols indicate stellar sub-classes following Sect. 4.1. The solid line shows the theoretical prediction by Vink et al. (2000, 2001). The dashed line is a fit through the O-type stars including both samples. The grey triangles are stars from Mokiem et al. (2007) that have only an upper limit in Ṁ and are excluded from the fit.