diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 2e70efa08b77..5d9b178484fd 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -903,6 +903,7 @@ static int usb_serial_probe(struct usb_interface *interface,
 		port->port.ops = &serial_port_ops;
 		port->serial = serial;
 		spin_lock_init(&port->lock);
+		init_waitqueue_head(&port->delta_msr_wait);
 		/* Keep this for private driver use for the moment but
 		   should probably go away */
 		INIT_WORK(&port->work, usb_serial_port_work);