diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 7ecf4ff..4d2b310 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -96,7 +96,8 @@
 	mutex_lock(&table_lock);
 	for (i = 0; i < num_ports; ++i) {
 		port = serial->port[i];
-		minor = idr_alloc(&serial_minors, port, 0, 0, GFP_KERNEL);
+		minor = idr_alloc(&serial_minors, port, 0,
+					USB_SERIAL_TTY_MINORS, GFP_KERNEL);
 		if (minor < 0)
 			goto error;
 		port->minor = minor;