diff --git a/net/eth.c b/net/eth.c
index dbd1e2d..5911b1c 100644
--- a/net/eth.c
+++ b/net/eth.c
@@ -108,6 +108,8 @@
 {
 	struct eth_device *dev, *target_dev;
 
+	BUG_ON(devname == NULL);
+
 	if (!eth_devices)
 		return NULL;