diff --git a/drivers/net/cpmac.c b/drivers/net/cpmac.c
index af305c0b34d1..cfb4198b6776 100644
--- a/drivers/net/cpmac.c
+++ b/drivers/net/cpmac.c
@@ -202,7 +202,7 @@ struct cpmac_priv {
 	void __iomem *regs;
 	struct mii_bus *mii_bus;
 	struct phy_device *phy;
-	char phy_name[BUS_ID_SIZE];
+	char phy_name[MII_BUS_ID_SIZE + 3];
 	int oldlink, oldspeed, oldduplex;
 	u32 msg_enable;
 	struct net_device *dev;