The measurement method for diffuse field sound absorption (ISO 354) is troubled with low reproducibility, far worse than can be accepted in respect to design of spaces, control of quality and legal security. This is caused by deviations from the basic assumption for the relation between sound absorption and reverberation time: the presence of a homogeneous and isotropic sound field. Research has been done to increase and quantify the diffusivity of the sound field in the room. It was found that indeed it is possible to improve the diffusivity but the only reliable indicator of the diffusivity is the sound absorption of the sample itself. Only improving the room will not take away the differences between laboratories. An ISO working group has made a working draft for the revision of ISO 354, that contains a qualification of the room with a minimum sound absorption of a reference absorber and correction of the outcome of every sample, based on the measurement result of the reference absorber.This working draft was circulated and commented. A basic outline of the method will be presented as well as a summary of the comments given.