diff --git a/drivers/net/tc35815.c b/drivers/net/tc35815.c
index 744f11f5ffb8fdb1d1d349442d0eeaae2dcc05e8..10e4e85da3fcae7af7e9435145f06dad72abd35f 100644
--- a/drivers/net/tc35815.c
+++ b/drivers/net/tc35815.c
@@ -766,7 +766,8 @@ static int tc_mii_init(struct net_device *dev)
 	lp->mii_bus.name = "tc35815_mii_bus";
 	lp->mii_bus.read = tc_mdio_read;
 	lp->mii_bus.write = tc_mdio_write;
-	lp->mii_bus.id = (lp->pci_dev->bus->number << 8) | lp->pci_dev->devfn;
+	snprintf(lp->mii_bus.id, MII_BUS_ID_SIZE, "%x",
+		 (lp->pci_dev->bus->number << 8) | lp->pci_dev->devfn);
 	lp->mii_bus.priv = dev;
 	lp->mii_bus.dev = &lp->pci_dev->dev;
 	lp->mii_bus.irq = kmalloc(sizeof(int) * PHY_MAX_ADDR, GFP_KERNEL);