--- 
+++ 
@@ -21,7 +21,7 @@
      * @return a new instance, with reversed direction
      */
     public Line revert() {
-        final Line reverted = new Line(zero, zero.subtract(direction));
+final Line reverted = new Line(zero, zero.subtract(direction));        reverted.direction = direction.negate();
         return reverted;
     }
 