diff --git a/dlls/msctf/msctf_internal.h b/dlls/msctf/msctf_internal.h
index 5dd823fe33e..03370bde2e0 100644
--- a/dlls/msctf/msctf_internal.h
+++ b/dlls/msctf/msctf_internal.h
@@ -65,6 +65,7 @@ extern CLSID get_textservice_clsid(TfClientId tid) DECLSPEC_HIDDEN;
 extern HRESULT get_textservice_sink(TfClientId tid, REFCLSID iid, IUnknown** sink) DECLSPEC_HIDDEN;
 extern HRESULT set_textservice_sink(TfClientId tid, REFCLSID iid, IUnknown* sink) DECLSPEC_HIDDEN;
 
-extern const WCHAR szwSystemTIPKey[];
-extern const WCHAR szwSystemCTFKey[];
+extern const WCHAR szwSystemTIPKey[] DECLSPEC_HIDDEN;
+extern const WCHAR szwSystemCTFKey[] DECLSPEC_HIDDEN;
+
 #endif /* __WINE_MSCTF_I_H */