diff --git a/drivers/comedi/drivers/aio_iiro_16.c b/drivers/comedi/drivers/aio_iiro_16.c
index d5d18fa2c638..52385b14a9a4 100644
--- a/drivers/comedi/drivers/aio_iiro_16.c
+++ b/drivers/comedi/drivers/aio_iiro_16.c
@@ -59,6 +59,9 @@ static irqreturn_t aio_iiro_16_cos(int irq, void *d)
 	unsigned int status;
 	unsigned int val;
 
+	if (!dev->attached)
+		return IRQ_NONE;
+
 	status = inb(dev->iobase + AIO_IIRO_16_STATUS);
 	if (!(status & AIO_IIRO_16_STATUS_IRQE))
 		return IRQ_NONE;