diff --git a/src/AIModel/AIBase.cxx b/src/AIModel/AIBase.cxx
index bb66a9b97..db006f9b3 100644
--- a/src/AIModel/AIBase.cxx
+++ b/src/AIModel/AIBase.cxx
@@ -81,6 +81,8 @@ FGAIBase::~FGAIBase() {
     root->removeChild(_type_str.c_str(), index);
     delete fp;
     fp = NULL;
+    ssgDeRefDelete(model);
+    model = 0;
 }
 
 void FGAIBase::update(double dt) {
diff --git a/src/ATC/AIEntity.cxx b/src/ATC/AIEntity.cxx
index 5736f2cbd..945668a15 100644
--- a/src/ATC/AIEntity.cxx
+++ b/src/ATC/AIEntity.cxx
@@ -45,7 +45,7 @@ FGAIEntity::FGAIEntity() {
 
 FGAIEntity::~FGAIEntity() {
 	//cout << "FGAIEntity dtor called..." << endl;
-	_model->deRef();	// Ought to check valid?
+        ssgDeRefDelete(_model);	// Ought to check valid?
 	//cout << "Removing model from scene graph..." << endl;
 	globals->get_scenery()->get_scene_graph()->removeKid(_aip.getSceneGraph());
         // Unregister that one at the scenery manager
diff --git a/src/ATC/AIMgr.cxx b/src/ATC/AIMgr.cxx
index 629d5d97b..c7c7c4744 100644
--- a/src/ATC/AIMgr.cxx
+++ b/src/ATC/AIMgr.cxx
@@ -57,8 +57,8 @@ FGAIMgr::FGAIMgr() {
 }
 
 FGAIMgr::~FGAIMgr() {
-	_defaultModel->deRef();
-	if(_havePiperModel) _piperModel->deRef();
+        ssgDeRefDelete(_defaultModel);
+	if(_havePiperModel) ssgDeRefDelete(_piperModel);
 }
 
 void FGAIMgr::init() {
diff --git a/src/Instrumentation/wxradar.cxx b/src/Instrumentation/wxradar.cxx
index a233433c1..a6dea2399 100644
--- a/src/Instrumentation/wxradar.cxx
+++ b/src/Instrumentation/wxradar.cxx
@@ -70,6 +70,8 @@ wxRadarBg::wxRadarBg ()
 
 wxRadarBg::~wxRadarBg ()
 {
+    ssgDeRefDelete(resultTexture);
+    ssgDeRefDelete(wxEcho);
 }
 
 void
diff --git a/src/Scenery/scenery.cxx b/src/Scenery/scenery.cxx
index 88badf93e..51e26ae67 100644
--- a/src/Scenery/scenery.cxx
+++ b/src/Scenery/scenery.cxx
@@ -123,8 +123,8 @@ void FGScenery::unregister_placement_transform(ssgPlacementTransform *trans) {
     placement_list_type::iterator it = _placement_list.begin();
     while (it != _placement_list.end()) {
         if ((*it) == trans) {
-            (*it)->deRef();
             it = _placement_list.erase(it);        
+            ssgDeRefDelete(trans);
         } else
             ++it;
     }