diff --git a/include/wx/html/helpfrm.h b/include/wx/html/helpfrm.h
index 026482fe44..c2a3782b75 100644
--- a/include/wx/html/helpfrm.h
+++ b/include/wx/html/helpfrm.h
@@ -64,7 +64,7 @@ class wxHtmlHelpMergedIndex;
 
 class WXDLLIMPEXP_FWD_CORE wxHelpControllerBase;
 class WXDLLIMPEXP_FWD_HTML wxHtmlHelpController;
-class WXDLLIMPEXP_FWD_BASE wxHtmlHelpWindow;
+class WXDLLIMPEXP_FWD_HTML wxHtmlHelpWindow;
 
 class WXDLLIMPEXP_HTML wxHtmlHelpFrame : public wxFrame
 {