diff --git a/drivers/staging/comedi/drivers/pcl816.c b/drivers/staging/comedi/drivers/pcl816.c
index f9a0dac79eca..1b1708a58b67 100644
--- a/drivers/staging/comedi/drivers/pcl816.c
+++ b/drivers/staging/comedi/drivers/pcl816.c
@@ -488,7 +488,9 @@ static int pcl816_ai_cmdtest(struct comedi_device *dev,
 	if (!cmd->scan_begin_src || tmp != cmd->scan_begin_src)
 		err++;
 
-	if (!(cmd->convert_src & (TRIG_EXT | TRIG_TIMER)))
+	tmp = cmd->convert_src;
+	cmd->convert_src &= TRIG_EXT | TRIG_TIMER;
+	if (!cmd->convert_src || tmp != cmd->convert_src)
 		err++;
 
 	tmp = cmd->scan_end_src;