diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c
index 24145c3..6cc4358 100644
--- a/drivers/tty/amiserial.c
+++ b/drivers/tty/amiserial.c
@@ -1073,8 +1073,10 @@
 		    (new_serial.close_delay != port->close_delay) ||
 		    (new_serial.xmit_fifo_size != state->xmit_fifo_size) ||
 		    ((new_serial.flags & ~ASYNC_USR_MASK) !=
-		     (port->flags & ~ASYNC_USR_MASK)))
+		     (port->flags & ~ASYNC_USR_MASK))) {
+			tty_unlock();
 			return -EPERM;
+		}
 		port->flags = ((port->flags & ~ASYNC_USR_MASK) |
 			       (new_serial.flags & ASYNC_USR_MASK));
 		state->custom_divisor = new_serial.custom_divisor;