diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c
index a2c3c0944f9961b72dc089496c544e4cf823b5ef..541046474c9ebd59d88e6e769072965dcdfa397c 100644
--- a/drivers/usb/serial/quatech2.c
+++ b/drivers/usb/serial/quatech2.c
@@ -540,7 +540,7 @@ static void qt2_process_read_urb(struct urb *urb)
 
 				newport = *(ch + 3);
 
-				if (newport > serial->num_ports) {
+				if (newport >= serial->num_ports) {
 					dev_err(&port->dev,
 						"%s - port change to invalid port: %i\n",
 						__func__, newport);