Incline for shower waste

Hi There,
I am currently installing a shower in my flat (assisted by a plumber). He has installed the pipework for the shower waste however I am concerned that the incline on the pipe may not be sufficient. (My plumber is not concerened...)
I have placed a spirit level on the pipe and it indicates a VERY slight downward incline. Can anyone tell me what the recommended incline is?
Any help would be greatly appreciated!
Regards

1/4" inch per foot.

Thanks!

Many thanks for your assistance - it is greatly appreciated!!

Don't get too concerned about the 1/4" per foot on a very short run. As long as the slope is away from the sink, you'll be OK.