diff --git a/samples/widgets/widgets.h b/samples/widgets/widgets.h
index e717e5ad08..11840de9f2 100644
--- a/samples/widgets/widgets.h
+++ b/samples/widgets/widgets.h
@@ -43,11 +43,11 @@
     #define ICON_SIZE         16
 #endif
 
-class WXDLLEXPORT wxCheckBox;
-class WXDLLEXPORT wxSizer;
-class WXDLLEXPORT wxImageList;
-class WXDLLEXPORT wxTextCtrl;
-class WXDLLEXPORT WidgetsBookCtrl;
+class WXDLLIMPEXP_FWD_CORE wxCheckBox;
+class WXDLLIMPEXP_FWD_CORE wxSizer;
+class WXDLLIMPEXP_FWD_CORE wxImageList;
+class WXDLLIMPEXP_FWD_CORE wxTextCtrl;
+class WXDLLIMPEXP_FWD_CORE WidgetsBookCtrl;
 
 class WidgetsPageInfo;