diff --git a/net/core/dev_mcast.c b/net/core/dev_mcast.c
index 9e2fa39f22a300e1fc46502aac39f305751e69c5..fd91569e2394b0b37caada596af21b29a5e2df3b 100644
--- a/net/core/dev_mcast.c
+++ b/net/core/dev_mcast.c
@@ -96,6 +96,8 @@ int dev_mc_add(struct net_device *dev, void *addr, int alen, int glbl)
 	int err;
 
 	netif_addr_lock_bh(dev);
+	if (alen != dev->addr_len)
+		return -EINVAL;
 	err = __dev_addr_add(&dev->mc_list, &dev->mc_count, addr, alen, glbl);
 	if (!err)
 		__dev_set_rx_mode(dev);