diff --git a/costmap_2d/include/costmap_2d/obstacle_layer.h b/costmap_2d/include/costmap_2d/obstacle_layer.h
index 372c364542..4aead83c19 100644
--- a/costmap_2d/include/costmap_2d/obstacle_layer.h
+++ b/costmap_2d/include/costmap_2d/obstacle_layer.h
@@ -158,8 +158,8 @@ class ObstacleLayer : public CostmapLayer
 
   laser_geometry::LaserProjection projector_; ///< @brief Used to project laser scans into point clouds
 
-  std::vector<boost::shared_ptr<tf::MessageFilterBase> > observation_notifiers_; ///< @brief Used to make sure that transforms are available for each sensor
   std::vector<boost::shared_ptr<message_filters::SubscriberBase> > observation_subscribers_; ///< @brief Used for the observation message filters
+  std::vector<boost::shared_ptr<tf::MessageFilterBase> > observation_notifiers_; ///< @brief Used to make sure that transforms are available for each sensor
   std::vector<boost::shared_ptr<costmap_2d::ObservationBuffer> > observation_buffers_; ///< @brief Used to store observations from various sensors
   std::vector<boost::shared_ptr<costmap_2d::ObservationBuffer> > marking_buffers_; ///< @brief Used to store observation buffers used for marking obstacles
   std::vector<boost::shared_ptr<costmap_2d::ObservationBuffer> > clearing_buffers_; ///< @brief Used to store observation buffers used for clearing obstacles