Inverted editor mouse position raycast

Hi, I'm currently working on a level editor and I'm trying to get the world position of the mouse in the scene view. I'm currently doing the following:

     void OnSceneGUI(){
         if(Event.current.type == EventType.mouseMove){
             ray = Camera.current.ScreenPointToRay(Event.current.mousePosition);
             if (Physics.Raycast(ray, out hit,10000,mask)){
                 GameObject.Find ("Cube").transform.position = hit.point;
             }
         }
     }

It works fairly well, however the z axis seems to react like it's mirror. Meaning if I move my mouse down the object will go up and vice versa. I've tried -hit.point.z in a Vector3 but that results in a weird offset. Does anyone know what I'm doing wrong?