diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index c6ff79360302..2e92c6fef683 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -585,6 +585,7 @@ static struct usb_serial_driver ch341_device = {
 		.owner	= THIS_MODULE,
 		.name	= "ch341-uart",
 	},
+	.bulk_in_size      = 512,
 	.id_table          = id_table,
 	.num_ports         = 1,
 	.open              = ch341_open,