diff --git a/drivers/net/stmmac/stmmac_main.c b/drivers/net/stmmac/stmmac_main.c
index 508fba8fa07f41a12ed0be5a8828b630dd885c24..79a93811787856ff174f4140916af1c733503b39 100644
--- a/drivers/net/stmmac/stmmac_main.c
+++ b/drivers/net/stmmac/stmmac_main.c
@@ -305,8 +305,8 @@ static int stmmac_init_phy(struct net_device *dev)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
 	struct phy_device *phydev;
-	char phy_id[BUS_ID_SIZE];	/* PHY to connect */
-	char bus_id[BUS_ID_SIZE];
+	char phy_id[MII_BUS_ID_SIZE + 3];
+	char bus_id[MII_BUS_ID_SIZE];
 
 	priv->oldlink = 0;
 	priv->speed = 0;
@@ -318,7 +318,8 @@ static int stmmac_init_phy(struct net_device *dev)
 	}
 
 	snprintf(bus_id, MII_BUS_ID_SIZE, "%x", priv->bus_id);
-	snprintf(phy_id, BUS_ID_SIZE, PHY_ID_FMT, bus_id, priv->phy_addr);
+	snprintf(phy_id, MII_BUS_ID_SIZE + 3, PHY_ID_FMT, bus_id,
+		 priv->phy_addr);
 	pr_debug("stmmac_init_phy:  trying to attach to %s\n", phy_id);
 
 	phydev = phy_connect(dev, phy_id, &stmmac_adjust_link, 0,