diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 0a566eea49c..f331e2bde88 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -974,6 +974,7 @@ int usb_serial_probe(struct usb_interface *interface,
 		if (retval > 0) {
 			/* quietly accept this device, but don't bind to a
 			   serial port as it's about to disappear */
+			serial->num_ports = 0;
 			goto exit;
 		}
 	}