Best way to shoot arrows from walls?

So we have a base with a wall and a walkway around it. We've got a half-wall up to keep ourselves from walking off the edge. But I find it really hard to shoot arrows over the walls towards creatures at the base – the arrow keeps getting hung up on the half-wall even if the target looks like it's pointing into clear space.

I futzed around in cheat mode building some machicolations, and those didn't really do any better – half the time even if I thought I had a clear shot downwards, it ended up in the walkway.

Is there a better way to do this? Or is this just the price of the game being relatively new and still under development?

The best strategy I can find is to stand way over to the side of your target, so that you're shooting more sideways than down. (And I know that the ultimate base defense is moats, we're just still relatively early in the game and are not ready to invest that much time in digging.)