Apparatuses comprising data processing circuitry and a wakeup interrupt controller and methods of operating the apparatuses are disclosed. Prior to the processing circuitry entering a low power state, indications of pending interrupts are transferred to the wakeup interrupt controller. Further indications of interrupts received whilst the processing circuitry is in the low power state may be accumulated in the wakeup interrupt controller. When the wakeup interrupt controller receives a wakeup signal, the indications of pending interrupts are transferred to the processing circuitry and the processing circuitry exits the low power state.