Convocation Cooldown Recovery Bug

The uber lab enchant 30% cooldown recovery speed for convocation is not working properly. Instead of reducing 30% of the 8 second cooldown you get 6.15 seconds as it's cooldown instead it being reduced by 2.4 seconds and being 5.4.

Also it's the same case when using the new harbinger unique belt that grants cooldown recovery speed, it isn't giving the proper cooldown reduction.

Using the two together should bring the cooldown to 4 seconds if the belt has it's 20% roll but as you can see it's even further off what it should be with both. It's been ages since I did simple math so if i'm right or misunderstanding something i'd appreciate a response

here is a image showing the values im talking about http://imgur.com/a/0QrwU

bump