diff --git a/[refs] b/[refs]
index c812821922f4..c2dcfbba1a9a 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7f1dc313d01f5f0f84c06051343a3b8623932d3c
+refs/heads/master: 7af25b4b34a2439020d78da765a3bed0ff73f25c
diff --git a/trunk/drivers/usb/class/cdc-acm.c b/trunk/drivers/usb/class/cdc-acm.c
index 85a1a55815cf..e3861b21e776 100644
--- a/trunk/drivers/usb/class/cdc-acm.c
+++ b/trunk/drivers/usb/class/cdc-acm.c
@@ -59,6 +59,7 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/tty.h>
+#include <linux/serial.h>
 #include <linux/tty_driver.h>
 #include <linux/tty_flip.h>
 #include <linux/module.h>
@@ -609,6 +610,7 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp)
 	acm->throttle = 0;
 
 	tasklet_schedule(&acm->urb_task);
+	set_bit(ASYNCB_INITIALIZED, &acm->port.flags);
 	rv = tty_port_block_til_ready(&acm->port, tty, filp);
 done:
 	mutex_unlock(&acm->mutex);