Context : Recent studies of O-type stars demonstrated that discrepant mass-loss rates are obtained when different diagnostic methods are employed – fitting the unsaturated UV resonance lines ( e.g .
P v ) gives drastically lower values than obtained from the H \alpha emission .
Wind inhomogeneity ( so-called “ clumping ” ) may be the main cause for this discrepancy .

Aims : In a previous paper , we have presented 3-D Monte-Carlo calculations for the formation of scattering lines in a clumped stellar wind .
In the present paper we select five O-type supergiants ( from O4 to O7 ) and test whether the reported discrepancies can be resolved this way .

Methods : In the first step , the analyses start with simulating the observed spectra with Potsdam Wolf-Rayet ( PoWR ) non-LTE model atmospheres .
The mass-loss rates are adjusted to fit best to the observed H \alpha emission lines .
For the unsaturated UV resonance lines ( i.e .
P v ) we then apply our 3-D Monte-Carlo code , which can account for wind clumps of any optical depths ( “ macroclumping ” ) , a non-void inter-clump medium , and a velocity dispersion inside the clumps .
The ionization stratifications and underlying photospheric spectra are adopted from the PoWR models .
From fitting the observed resonance line profiles , the properties of the wind clumps are constrained .

Results : Our results show that with the mass-loss rates that fit H \alpha ( and other Balmer and He ii lines ) , the UV resonance lines ( especially the unsaturated doublet of P v ) can also be reproduced without problem when macroclumping is taken into account .
There is no need to artificially reduce the mass-loss rates , nor to assume a sub-solar phosphorus abundance or an extremely high clumping factor , contrary to what was claimed by other authors .
These consistent mass-loss rates are lower by a factor of 1.3 to 2.6 , compared to the mass-loss rate recipe from Vink et al .

Conclusions : Macroclumping resolves the previously reported discrepancy between H \alpha and P v mass-loss diagnostics .