diff --git a/drivers/staging/comedi/drivers/s626.c b/drivers/staging/comedi/drivers/s626.c
index 6815cfe2664e42e632114b3e87ca140b349008f3..b486099b543d56e61a14e94b3bc698c58cc04cb0 100644
--- a/drivers/staging/comedi/drivers/s626.c
+++ b/drivers/staging/comedi/drivers/s626.c
@@ -494,7 +494,7 @@ static void s626_send_dac(struct comedi_device *dev, uint32_t val)
  * Private helper function: Write setpoint to an application DAC channel.
  */
 static void s626_set_dac(struct comedi_device *dev, uint16_t chan,
-			 unsigned short dacdata)
+			 int16_t dacdata)
 {
 	struct s626_private *devpriv = dev->private;
 	uint16_t signmask;