diff --git a/net/dsa/master.c b/net/dsa/master.c
index a25242e71fb2f3e485da8d43bc7a63db2977b991..d7d5145aa2351a145fef00030a87785b2601e011 100644
--- a/net/dsa/master.c
+++ b/net/dsa/master.c
@@ -158,7 +158,7 @@ static void dsa_master_ethtool_teardown(struct net_device *dev)
 	cpu_dp->orig_ethtool_ops = NULL;
 }
 
-void dsa_master_set_mtu(struct net_device *dev, struct dsa_port *cpu_dp)
+static void dsa_master_set_mtu(struct net_device *dev, struct dsa_port *cpu_dp)
 {
 	unsigned int mtu = ETH_DATA_LEN + cpu_dp->tag_ops->overhead;
 	int err;