diff --git a/drivers/usb/serial/whiteheat.c b/drivers/usb/serial/whiteheat.c
index b9fca3586d741003a50ffb435be7de74020c48e8..347caad47a121d3f7a26ec7f3246a6960114ffc2 100644
--- a/drivers/usb/serial/whiteheat.c
+++ b/drivers/usb/serial/whiteheat.c
@@ -649,7 +649,7 @@ static void firm_setup_port(struct tty_struct *tty)
 	struct whiteheat_port_settings port_settings;
 	unsigned int cflag = tty->termios.c_cflag;
 
-	port_settings.port = port->number + 1;
+	port_settings.port = port->number - port->serial->minor + 1;
 
 	/* get the byte size */
 	switch (cflag & CSIZE) {