diff --git a/sys/dev/netif/mii_layer/mlphy.c b/sys/dev/netif/mii_layer/mlphy.c
--- a/sys/dev/netif/mii_layer/mlphy.c
+++ b/sys/dev/netif/mii_layer/mlphy.c
@@ -217,7 +217,8 @@
 	}
 	kfree(devlist, M_TEMP);
 
-	KKASSERT(ife->ifm_data >= 0 && ife->ifm_data < MII_NMEDIA);
+	if (ife->ifm_data < 0 || ife->ifm_data >= MII_NMEDIA)
+		return (0);
 	mm = &mii_media_table[ife->ifm_data];
 
 	switch (cmd) {