diff --git a/src/common/sizer.cpp b/src/common/sizer.cpp
index a8abbb3445..1d9e4c216b 100644
--- a/src/common/sizer.cpp
+++ b/src/common/sizer.cpp
@@ -2002,12 +2002,16 @@ wxSize wxBookCtrlSizer::CalcMin()
 
 #if wxUSE_NOTEBOOK
 
+#if WXWIN_COMPATIBILITY_2_6
+
 wxNotebookSizer::wxNotebookSizer(wxNotebook *nb)
 {
     wxASSERT_MSG( nb, wxT("wxNotebookSizer needs a control") );
     m_bookctrl = nb;
 }
 
+#endif // WXWIN_COMPATIBILITY_2_6
+
 #endif // wxUSE_NOTEBOOOK
 #endif // wxUSE_BOOKCTRL