diff --git a/source/gui/detail/bedrock_windows.cpp b/source/gui/detail/bedrock_windows.cpp
index 58044bb9..a7ccb6c4 100644
--- a/source/gui/detail/bedrock_windows.cpp
+++ b/source/gui/detail/bedrock_windows.cpp
@@ -1,7 +1,7 @@
 /**
  *	A Bedrock Implementation
  *	Nana C++ Library(http://www.nanapro.org)
- *	Copyright(C) 2003-2019 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2003-2020 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0.
  *	(See accompanying file LICENSE_1_0.txt or copy at
@@ -1191,9 +1191,7 @@ namespace detail
 					}
 					else if (pointer_wd != root_window)
 					{
-						DWORD pid = 0;
-						::GetWindowThreadProcessId(pointer_wd, &pid);
-						if (pid == ::GetCurrentProcessId())
+						if (::GetWindowThreadProcessId(pointer_wd, nullptr) != ::GetCurrentThreadId())
 							::PostMessage(pointer_wd, message, wParam, lParam);
 					}
 				}