diff --git a/drivers/comedi/drivers/pcmmio.c b/drivers/comedi/drivers/pcmmio.c
index d38202c8a12b..f42b7343b4e4 100644
--- a/drivers/comedi/drivers/pcmmio.c
+++ b/drivers/comedi/drivers/pcmmio.c
@@ -362,6 +362,9 @@ static irqreturn_t interrupt_pcmmio(int irq, void *d)
 	unsigned int triggered;
 	unsigned char int_pend;
 
+	if (!dev->attached)
+		return IRQ_NONE;
+
 	/* are there any interrupts pending */
 	int_pend = inb(dev->iobase + PCMMIO_INT_PENDING_REG) & 0x07;
 	if (!int_pend)