diff --git a/reactos/include/psdk/objbase.h b/reactos/include/psdk/objbase.h
index a5bfe187963..57da913bf51 100644
--- a/reactos/include/psdk/objbase.h
+++ b/reactos/include/psdk/objbase.h
@@ -510,6 +510,7 @@ typedef struct tagSTGOPTIONS
     const WCHAR* pwcsTemplateFile;
 } STGOPTIONS;
 
+HRESULT WINAPI StringFromIID(REFIID rclsid, LPOLESTR *lplpsz);
 HRESULT WINAPI StgCreateDocfile(LPCOLESTR pwcsName,DWORD grfMode,DWORD reserved,IStorage **ppstgOpen);
 HRESULT WINAPI StgCreateStorageEx(const WCHAR*,DWORD,DWORD,DWORD,STGOPTIONS*,void*,REFIID,void**);
 HRESULT WINAPI StgIsStorageFile(LPCOLESTR fn);