diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 6e9f619c491f..963630c65ca9 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -49,13 +49,13 @@ int mdiobus_register(struct mii_bus *bus)
 	int i;
 	int err = 0;
 
-	mutex_init(&bus->mdio_lock);
-
 	if (NULL == bus || NULL == bus->name ||
 			NULL == bus->read ||
 			NULL == bus->write)
 		return -EINVAL;
 
+	mutex_init(&bus->mdio_lock);
+
 	if (bus->reset)
 		bus->reset(bus);