diff --git a/src/osg/OcclusionQueryNode.cpp b/src/osg/OcclusionQueryNode.cpp
index 71c3e4cf7..41a946cab 100644
--- a/src/osg/OcclusionQueryNode.cpp
+++ b/src/osg/OcclusionQueryNode.cpp
@@ -101,12 +101,16 @@ struct RetrieveQueriesCallback : public osg::Camera::DrawCallback
     typedef std::vector<osg::ref_ptr<osg::TestResult> > ResultsVector;
     ResultsVector _results;
 
-    RetrieveQueriesCallback( osg::GLExtensions* ext=NULL )
-      : _extensionsFallback( ext )
+    RetrieveQueriesCallback( osg::GLExtensions* ext=NULL )  :
+        _extensionsFallback( ext )
+    {
+    }
+
+    RetrieveQueriesCallback( const RetrieveQueriesCallback& rqc, const osg::CopyOp& ) :
+        _extensionsFallback( rqc._extensionsFallback )
     {
     }
 
-    RetrieveQueriesCallback( const RetrieveQueriesCallback&, const osg::CopyOp& ) {}
     META_Object( osgOQ, RetrieveQueriesCallback )
 
     virtual void operator() (const osg::Camera& camera) const