diff --git a/PySide/QtDeclarative/typesystem_declarative.xml b/PySide/QtDeclarative/typesystem_declarative.xml
index 5649bf2..e754006 100644
--- a/PySide/QtDeclarative/typesystem_declarative.xml
+++ b/PySide/QtDeclarative/typesystem_declarative.xml
@@ -97,7 +97,7 @@
     <object-type name="QDeclarativeImageProvider">
         <enum-type name="ImageType" />
     </object-type>
-    <object-type name="QDeclarativeItem">
+    <object-type name="QDeclarativeItem" polymorphic-id-expression="qgraphicsitem_cast&lt;QDeclarativeItem*>(%1)">
         <extra-includes>
             <include file-name="pysideqmlregistertype.h" location="local"/>
         </extra-includes>
diff --git a/PySide/QtGui/typesystem_gui_common.xml b/PySide/QtGui/typesystem_gui_common.xml
index 676829e..1d1ea01 100644
--- a/PySide/QtGui/typesystem_gui_common.xml
+++ b/PySide/QtGui/typesystem_gui_common.xml
@@ -5584,7 +5584,7 @@
   <object-type name="QGraphicsEffectSource"/>
   -->
 
-  <object-type name="QGraphicsObject"/>
+  <object-type name="QGraphicsObject" polymorphic-id-expression="qgraphicsitem_cast&lt;QGraphicsObject*>(%1)" />
   <object-type name="QGraphicsOpacityEffect"/>
   <object-type name="QGraphicsRotation"/>
   <object-type name="QGraphicsScale"/>