diff --git a/drivers/serial/serial_arc.c b/drivers/serial/serial_arc.c
index 980b38d..70dbc6d 100644
--- a/drivers/serial/serial_arc.c
+++ b/drivers/serial/serial_arc.c
@@ -126,6 +126,7 @@
 	.id	= UCLASS_SERIAL,
 	.of_match = arc_serial_ids,
 	.ofdata_to_platdata = arc_serial_ofdata_to_platdata,
+	.platdata_auto_alloc_size = sizeof(struct arc_serial_platdata),
 	.probe = arc_serial_probe,
 	.ops	= &arc_serial_ops,
 };