diff --git a/drivers/serial/serial_s5p.c b/drivers/serial/serial_s5p.c
index feba467..8590dfd 100644
--- a/drivers/serial/serial_s5p.c
+++ b/drivers/serial/serial_s5p.c
@@ -174,8 +174,8 @@
 		return -EINVAL;
 
 	plat->reg = (struct s5p_uart *)addr;
-	plat->port_id = fdtdec_get_int(gd->fdt_blob, dev->of_offset, "id", -1);
-
+	plat->port_id = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
+					"id", dev->seq);
 	return 0;
 }