diff --git a/include/wx/html/helpfrm.h b/include/wx/html/helpfrm.h
index ed6e6f8e0e..f85e36ee5d 100644
--- a/include/wx/html/helpfrm.h
+++ b/include/wx/html/helpfrm.h
@@ -36,6 +36,8 @@
 
 class WXDLLIMPEXP_CORE wxButton;
 class WXDLLIMPEXP_CORE wxTextCtrl;
+class WXDLLIMPEXP_CORE wxTreeEvent;
+class WXDLLIMPEXP_CORE wxTreeCtrl;
 
 
 // style flags for the Help Frame
diff --git a/include/wx/html/htmlwin.h b/include/wx/html/htmlwin.h
index da9d6431a9..f23709848d 100644
--- a/include/wx/html/htmlwin.h
+++ b/include/wx/html/htmlwin.h
@@ -21,7 +21,6 @@
 #include "wx/window.h"
 #include "wx/scrolwin.h"
 #include "wx/config.h"
-#include "wx/treectrl.h"
 #include "wx/html/winpars.h"
 #include "wx/html/htmlcell.h"
 #include "wx/filesys.h"