Try and land with both feet levelled horizontal. I find that if one feet is lower than the other, especially the foot next to the wall, I tend to lean to that side more resulting in me putting that foot down.
EDIT: Not completely horizontal, but if you land with the foot that's away from the wall slightly lower, should help. I'm guessing you're putting your foot down that's next to the wall cos you're leaning to that side too much.