diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index a091db3..451f6b8 100644
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -546,7 +546,7 @@
 	priv->oldspeed = 0;
 	priv->oldduplex = -1;
 
-	snprintf(phy_id, BUS_ID_SIZE, PHY_ID_FMT, priv->einfo->bus_id, priv->einfo->phy_id);
+	snprintf(phy_id, sizeof(phy_id), PHY_ID_FMT, priv->einfo->bus_id, priv->einfo->phy_id);
 
 	interface = gfar_get_interface(dev);