diff --git a/include/WinStd/Common.h b/include/WinStd/Common.h
index dcebc37b..df028a1b 100644
--- a/include/WinStd/Common.h
+++ b/include/WinStd/Common.h
@@ -914,6 +914,9 @@ namespace winstd
         handle(_In_ const handle<handle_type, INVAL> &h) noexcept {};
         handle<handle_type, INVAL>& operator=(_In_ const handle<handle_type, INVAL> &h) noexcept {};
 
+        // Force use of valid() method when testing handle.
+        operator bool() const;
+
     public:
         ///
         /// Attaches already available object handle.