A circuit for shaping an input current of a switching power converter. The circuit is a power factor circuit comprising an input to be coupled to receive a rectified line signal, an output, a resistance coupled to resist a flow of current from the input to the output. The resistance has a first value and a switch coupled in parallel with the resistance and coupled to switch from a less conductive state into a more conductive state in response to the flow of current through the input, and the more conductive state is sufficiently conductive to divert a portion of the current flow away from the resistance.