Alpha problem with Mist in BGE

Hi, my problem is that using mist every object is clearly white stroked once it reaches mist depth.

Is there a way to avoid this?

Here’s the file:

https://drive.google.com/file/d/0Bzjaz9C7WgsFb05MUlF3aEVxdzg/view?usp=sharing

WASD + SPACEBAR to fire; fireball and fire placed in layer 2

Thank you in advance