diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 2db917eab799..8a521b5ea769 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -851,6 +851,7 @@ 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,