Using the normal 2-screw mechanism to mount the Nävlinge wall light, the lamp could easily rotate from side to side. I made a wall plate that the light can slide on, keeping it firmly in place.

Have the "UP" text facing towards you (and right way up) while screwing it to the wall. Then just slide the lamp onto it. This is because the lamp bracket has a slight angle to it.

The holes are at the same spacing as the original screws so you can re-use the same holes if you use this to fix the rotation issue like I did.

Print it with the larger side (with "UP") down, no support needed.