diff --git a/drivers/comedi/drivers/dt2811.c b/drivers/comedi/drivers/dt2811.c
index bcc4b5ef48e8..0438b8c90e44 100644
--- a/drivers/comedi/drivers/dt2811.c
+++ b/drivers/comedi/drivers/dt2811.c
@@ -193,13 +193,16 @@ static irqreturn_t dt2811_interrupt(int irq, void *d)
 {
 	struct comedi_device *dev = d;
 	struct comedi_subdevice *s = dev->read_subdev;
-	struct comedi_async *async = s->async;
-	struct comedi_cmd *cmd = &async->cmd;
+	struct comedi_async *async;
+	struct comedi_cmd *cmd;
 	unsigned int status;
 
 	if (!dev->attached)
 		return IRQ_NONE;
 
+	async = s->async;
+	cmd = &async->cmd;
+
 	status = inb(dev->iobase + DT2811_ADCSR_REG);
 
 	if (status & DT2811_ADCSR_ADERROR) {