diff --git a/src/xrc/xh_sizer.cpp b/src/xrc/xh_sizer.cpp
index d8652b6113..5ce46b41bd 100644
--- a/src/xrc/xh_sizer.cpp
+++ b/src/xrc/xh_sizer.cpp
@@ -186,11 +186,9 @@ wxObject* wxSizerXmlHandler::Handle_sizer()
     wxCHECK_MSG(m_parentSizer != NULL ||
                 (parentNode && parentNode->GetType() == wxXML_ELEMENT_NODE &&
                  m_parentAsWindow != NULL &&
-                 (m_parentAsWindow->IsKindOf(CLASSINFO(wxPanel)) ||
-                  m_parentAsWindow->IsKindOf(CLASSINFO(wxFrame)) ||
-                  m_parentAsWindow->IsKindOf(CLASSINFO(wxDialog)))
+                 (m_parentAsWindow->IsKindOf(CLASSINFO(wxWindow)))
                     ), NULL,
-                wxT("Incorrect use of sizer: parent is not 'wxDialog', 'wxFrame' or 'wxPanel'."));
+                wxT("Incorrect use of sizer: parent is not a 'wxWindow'."));
 
     if (m_class == wxT("wxBoxSizer"))
         sizer = Handle_wxBoxSizer();