glossy shading erroron plane object

http://i.imgur.com/X7dmVVf.png

I just noticed this weird shading error, I just used a glossy shader and hrd lighting. It appears only on areas, where the mesh has some very strong angles going on. Changing the lighting did not work as well as changing the roughness… When I added a subsurf modifier, it looked normal though… Is there any workaround for this problem, so that I can enjoy my low poly models?

No blend file supplied !! Why not ?? We have to rely on guesswork ??

Do you have faces with > 4 sides ? If so you are relying on the renderer to triangulate and you may get bad results.
But who knows, we can’t see what you can see !!

Sorry, forgot it