Pronterface G-Code View is Skewing object off center

Hi all, I recently got a Mini Kossel up and running. I'm trying to get the model preview feature in pronterface to function correctly. Currently, I slice with Slic3r and open/run the job with pronterface (when not SD printing). Look at the attached screenview from pronterface for a 20mm calibration cube. It's skewed.

In slic3r,I have my printer x at 170 and the y at 170 with center at 0,0. In pronterface options, I have the width and depth set to 170 on both with x home and y home both at 0.

How do I fix the skew?

Try setting the X and Y offset to 85.