Fog Effect Horizon Flicker

I am setting up a scene using deferred lighting and in order to get accurate fog I attached the fog image effect script to my camera. However, when I move around in my world I can see the far clipping plan flickering in the distance at the point where my terrain or objects are being 'clipped'. My far clipping plane is set to 45 and extending it doesn't seem to fix the issue.

(Note: I am using Unity 5.0.0b11)

Does anyone know the cause of this or any issues like this with the Unity supplied in fog image effect? Maybe the fog isn't accurately grading the density from clear to fully obstructed by the end of the far clipping plane?