diff --git a/libtest.png b/libtest.png
index 1841c94..097e057 100644
Binary files a/libtest.png and b/libtest.png differ
diff --git a/tests/png/stepper_motors.png b/tests/png/stepper_motors.png
index a4a0da5..daee793 100644
Binary files a/tests/png/stepper_motors.png and b/tests/png/stepper_motors.png differ
diff --git a/tests/stepper_motors.scad b/tests/stepper_motors.scad
index cd735bc..eca6d00 100644
--- a/tests/stepper_motors.scad
+++ b/tests/stepper_motors.scad
@@ -28,7 +28,7 @@ module stepper_motors()
             NEMA(stepper_motors[$i]);
 
         translate_z(4)
-            NEMA_screws(stepper_motors[$i], M3_pan_screw, n = $i, earth = $i > 4 ? undef : 0);
+            NEMA_screws(stepper_motors[$i], M3_pan_screw, n = $i, earth = $i > 4 ? undef : $i - 1);
     }
 
 if($preview)