diff --git a/drivers/usb/serial/kobil_sct.c b/drivers/usb/serial/kobil_sct.c
index c113a2a0e10c..bd5bd8589e04 100644
--- a/drivers/usb/serial/kobil_sct.c
+++ b/drivers/usb/serial/kobil_sct.c
@@ -345,7 +345,8 @@ static void kobil_close(struct usb_serial_port *port)
 
 	/* FIXME: Add rts/dtr methods */
 	if (port->write_urb) {
-		usb_kill_urb(port->write_urb);
+		usb_poison_urb(port->write_urb);
+		kfree(port->write_urb->transfer_buffer);
 		usb_free_urb(port->write_urb);
 		port->write_urb = NULL;
 	}