A power transmitter is configured to transfer power to a power receiver using a wireless inductive power signal. The power transmitter includes a power signal generator configured to drive an inductor to provide the power signal to an inductor of the power receiver. A power loop control is employed by the power receiver for providing power control error messages to the power transmitter, which also includes a query message processor configured to detect a query message from the power receiver using load modulation of the power signal. A modification processor of the power receiver is configured to modify a response of the power loop controller to the power control error messages dependent on the query message. The power receiver is configured to detect the modifications to the operation of the power control and interpret this as a response from the power transmitter to the query message from the power receiver.