diff --git a/drivers/staging/comedi/drivers/comedi_test.c b/drivers/staging/comedi/drivers/comedi_test.c
index fb3d09323ba1..01de996239f1 100644
--- a/drivers/staging/comedi/drivers/comedi_test.c
+++ b/drivers/staging/comedi/drivers/comedi_test.c
@@ -345,7 +345,7 @@ static int waveform_ai_cancel(struct comedi_device *dev,
 	struct waveform_private *devpriv = dev->private;
 
 	devpriv->timer_running = 0;
-	del_timer(&devpriv->timer);
+	del_timer_sync(&devpriv->timer);
 	return 0;
 }