diff --git a/drivers/net/sh_eth.c b/drivers/net/sh_eth.c
index cdd73b9c553d..0709b7512467 100644
--- a/drivers/net/sh_eth.c
+++ b/drivers/net/sh_eth.c
@@ -964,7 +964,7 @@ static void sh_eth_adjust_link(struct net_device *ndev)
 static int sh_eth_phy_init(struct net_device *ndev)
 {
 	struct sh_eth_private *mdp = netdev_priv(ndev);
-	char phy_id[BUS_ID_SIZE];
+	char phy_id[MII_BUS_ID_SIZE + 3];
 	struct phy_device *phydev = NULL;
 
 	snprintf(phy_id, sizeof(phy_id), PHY_ID_FMT,