diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
index 484b6a3c9b03..302909ccf183 100644
--- a/drivers/tty/mxser.c
+++ b/drivers/tty/mxser.c
@@ -2643,9 +2643,9 @@ static int mxser_probe(struct pci_dev *pdev,
 				mxvar_sdriver, brd->idx + i, &pdev->dev);
 		if (IS_ERR(tty_dev)) {
 			retval = PTR_ERR(tty_dev);
-			for (i--; i >= 0; i--)
+			for (; i > 0; i--)
 				tty_unregister_device(mxvar_sdriver,
-					brd->idx + i);
+					brd->idx + i - 1);
 			goto err_relbrd;
 		}
 	}
@@ -2751,9 +2751,9 @@ static int __init mxser_module_init(void)
 			tty_dev = tty_port_register_device(&brd->ports[i].port,
 					mxvar_sdriver, brd->idx + i, NULL);
 			if (IS_ERR(tty_dev)) {
-				for (i--; i >= 0; i--)
+				for (; i > 0; i--)
 					tty_unregister_device(mxvar_sdriver,
-						brd->idx + i);
+						brd->idx + i - 1);
 				for (i = 0; i < brd->info->nports; i++)
 					tty_port_destroy(&brd->ports[i].port);
 				free_irq(brd->irq, brd);