Fix: Negative numbers.

![screen079x50](https://f.cloud.github.com/assets/3616568/1389815/4e16a6a2-3be1-11e3-9dc9-bd200c03f9ca.png)

![screen081x50](https://f.cloud.github.com/assets/3616568/1389817/56b3e66c-3be1-11e3-8bab-bbae496b2b0f.png)