diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 59cc5d4df621..f23765ea6f65 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -366,6 +366,7 @@ static int ksz9021_config_init(struct phy_device *phydev)
 #define KSZ9031_PS_TO_REG		60
 
 /* Extended registers */
+/* MMD Address 0x2 */
 #define MII_KSZ9031RN_CONTROL_PAD_SKEW	4
 #define MII_KSZ9031RN_RX_DATA_PAD_SKEW	5
 #define MII_KSZ9031RN_TX_DATA_PAD_SKEW	6