Merged shapes anti-alias differently in Photoshop, any workaround?

For some reason, when two shapes (in my case, lines) in different orientations are combined into one layer, they alias different than expected.

To present what my issue is, here is how to replicate the strange behavior:

• Start up Photoshop and create a basic blank document, I used 500x500.


• Grab the line tool, create a new layer, and begin drawing a diagonal line. Hold shift to align it at 45deg.


• Create another new layer, and draw a horizontal line. It should look like this:

• Now, select both layers, right click, and "Merge Shapes". To illustrate how it changes, I moved the diagonal line a bit – you can see how the vertical line (and the horizontal line) both have strange anti-aliasing now.

If anyone has any idea how to prevent this, that would be awesome. I'm looking to export a single layer of merged shapes as a vector for use on my website, but this issue prevents me from doing that.

All help is appreciated. Thanks!