Interrupt request detection circuitry is disclosed for detecting and outputting interrupt requests to a processor. The interrupt request detection circuitry comprises: an interrupt signal input for receiving an interrupt signal; an input for receiving a signal from the processor indicating whether the processor is currently processing an interrupt; a detection circuit for detecting an interrupt request and outputting an interrupt request signal to a data processing apparatus; disabling logic for disabling at least a portion of the detection circuitry; wherein in response to detecting the processor is currently processing an interrupt; the detection circuit is configured to detect a change in value of the interrupt signal caused by assertion of the interrupt signal indicating an interrupt request and to output an interrupt request signal to output circuitry in response to detecting the interrupt signal assertion; and in response to detecting the processor is not currently processing an interrupt; the disabling logic is configured to disable at least a portion of the detection circuit; and the detection circuit with the at least a portion disabled, is configured to output the interrupt signal as the interrupt request signal to the output circuitry.