diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 0147ea39340e25d38107507e31e615428f7841e4..1ded83b66af0979c0f869db5e3c29c82e664c6ff 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -489,6 +489,7 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp)
 	else
 		rv = 0;
 
+	set_bit(TTY_NO_WRITE_SPLIT, &tty->flags);
 	tty->driver_data = acm;
 	acm->tty = tty;