Fix Wrong MAC address by "Change MAC address"

Part 1 of #7088

wrong
![1](https://cloud.githubusercontent.com/assets/2177532/5029487/7325f142-6b82-11e4-86ea-1f7a9c1e4c20.jpg)

fixed
![3](https://cloud.githubusercontent.com/assets/2177532/5029499/8d823370-6b82-11e4-94ec-ac4c36dd0fb1.jpg)