Rake runner isn't compatible with test-unit-2.0.0.0

I'm attempting to setup a build configuration for a simple Ruby project.

I've downloaded & installed ruby 2.0.0.0 via the installer package

C:\Users\misztalm>gem list

*** LOCAL GEMS ***

bigdecimal (1.2.0)
io-console (0.4.2)
json (1.7.7)
minitest (4.3.2)
psych (2.0.0)
rake (0.9.6)
rdoc (4.0.0)
test-unit (2.0.0.0)

I'm attempting to configure a Rake runner, but I'm getting the following error.

Rake runner isn't compatible with your'test-unit-2.0.0.0'(C:\Ruby200-x64\lib\ruby\gems\2.0.0\gems\test-unit-2.0.0.0) gem. Please submit a feature request.

I'm unable to downgrade/delete the test-unit gem, I've attempted to manually set the rake version to 0.9.6 but it didn't have any effect, I'm out of ideas so I need to as for your assistance, please tell me how do I make this work?