diff --git a/drivers/w1/masters/ds2490.c b/drivers/w1/masters/ds2490.c
index 299e274..b63b5e04 100644
--- a/drivers/w1/masters/ds2490.c
+++ b/drivers/w1/masters/ds2490.c
@@ -233,7 +233,7 @@
 {
 	int count, err;
 
-	memset(st, 0, sizeof(st));
+	memset(st, 0, sizeof(*st));
 
 	count = 0;
 	err = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, dev->ep[EP_STATUS]), buf, size, &count, 100);