diff --git a/drivers/staging/comedi/kcomedilib/kcomedilib_main.c b/drivers/staging/comedi/kcomedilib/kcomedilib_main.c
index 7dc5a18e69d42bd4bd8e9df3d2458d368f769753..8777f958c04145e2a9228918a35c89518393bfb5 100644
--- a/drivers/staging/comedi/kcomedilib/kcomedilib_main.c
+++ b/drivers/staging/comedi/kcomedilib/kcomedilib_main.c
@@ -41,7 +41,8 @@ struct comedi_device *comedi_open(const char *filename)
 	if (strncmp(filename, "/dev/comedi", 11) != 0)
 		return NULL;
 
-	minor = simple_strtoul(filename + 11, NULL, 0);
+	if (kstrtouint(filename + 11, 0, &minor))
+		return NULL;
 
 	if (minor >= COMEDI_NUM_BOARD_MINORS)
 		return NULL;