diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
index 000b95787df1..bd6129db6417 100644
--- a/drivers/of/of_mdio.c
+++ b/drivers/of/of_mdio.c
@@ -362,7 +362,7 @@ struct phy_device *of_phy_get_and_connect(struct net_device *dev,
 	int ret;
 
 	iface = of_get_phy_mode(np);
-	if (iface < 0)
+	if ((int)iface < 0)
 		return NULL;
 	if (of_phy_is_fixed_link(np)) {
 		ret = of_phy_register_fixed_link(np);