Is there a trick to making 9patch images with single pixel borders?

I'm not talking about the single pixel black borders that you use to define the stretchable and content areas. I'm talking about the image itself. If I create an image that has a 1 pixel border around it, often times android will pick one of the edges and stretch it to 2 (or sometimes more) pixels, even though I specifically left the edges out of the stretchable area in the draw9patch utility.