diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 3ff7b92..51df337 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -117,14 +117,16 @@
 		/*
 		 * No locking required for CPU-local interrupts:
 		 */
-		desc->handler->ack(irq);
+		if (desc->handler->ack)
+			desc->handler->ack(irq);
 		action_ret = handle_IRQ_event(irq, regs, desc->action);
 		desc->handler->end(irq);
 		return 1;
 	}
 
 	spin_lock(&desc->lock);
-	desc->handler->ack(irq);
+	if (desc->handler->ack)
+		desc->handler->ack(irq);
 	/*
 	 * REPLAY is when Linux resends an IRQ that was dropped earlier
 	 * WAITING is used by probe to mark irqs that are being tested