diff --git a/drivers/staging/comedi/drivers/adl_pci9118.c b/drivers/staging/comedi/drivers/adl_pci9118.c
index 93b41e6712a6cbc369a13111a43d6aa19182ca71..2aef881b6ee41965453c110d0fd1f6aee44c3935 100644
--- a/drivers/staging/comedi/drivers/adl_pci9118.c
+++ b/drivers/staging/comedi/drivers/adl_pci9118.c
@@ -586,8 +586,9 @@ static void pci9118_ai_munge(struct comedi_device *dev,
 			     unsigned int start_chan_index)
 {
 	struct pci9118_private *devpriv = dev->private;
-	unsigned int i, num_samples = num_bytes / sizeof(short);
 	unsigned short *array = data;
+	unsigned int num_samples = comedi_bytes_to_samples(s, num_bytes);
+	unsigned int i;
 
 	for (i = 0; i < num_samples; i++) {
 		if (devpriv->usedma)