A transmission power allocation method for a transmitter is disclosed. The transmitter comprises a number of at least two transmitter paths for spatial multiplexing of two or more signals to be transmitted using respective allocated transmission powers to respective ones of two or more users, wherein each transmitter path comprises at least one component causing non-linear distortion and a transmit antenna. The method comprises determining a respective received distortion power for each of the two or more users as a function of respective hypothesized transmission powers for the two or more users and based on a model of a spatial behavior of the non-linear distortion. The method also comprises allocating respective transmission powers for the two or more users based on the determined respective received distortion powers. Corresponding transmission power allocation apparatus, transmitter, network node, wireless communication device, and computer program product are also disclosed.