fix issue #173 (segfault on dot execution)
fix issue #173 (segfault on dot execution)

kirbyfan64/kona,pahihu/kona,0branch/kona,pahihu/kona,igaray/kona,pahihu/kona,moussazeghida/kona,igaray/kona,igaray/kona,moussazeghida/kona,kevinlawler/kona,moussazeghida/kona,kaostao/kona,0branch/kona,kevinlawler/kona,kirbyfan64/kona,singaraiona/kona,joebo/kona,joebo/kona,kirbyfan64/kona,kaostao/kona,singaraiona/kona,kaostao/kona,0branch/kona,joebo/kona