diff --git a/src/osgUtil/Optimizer.cpp b/src/osgUtil/Optimizer.cpp
index c1e25d1d9..6ef9e4c08 100644
--- a/src/osgUtil/Optimizer.cpp
+++ b/src/osgUtil/Optimizer.cpp
@@ -1099,6 +1099,12 @@ bool CollectLowestTransformsVisitor::removeTransforms(osg::Node* nodeWeCannotRem
         titr!=_transformMap.end();
         ++titr)
     {
+        if (titr->first==0)
+        {
+            OSG_NOTICE<<"Warning: CollectLowestTransformsVisitor::removeTransforms() error, encountered a NULL Transform pointer"<<std::endl;
+            break;
+        }
+
         if (titr->second._canBeApplied)
         {
             if (titr->first!=nodeWeCannotRemove)