diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 4f8367eaff0eca9a3888b46bea90cfaf264e22e3..ea1a571ccd1730e9ecc021b22bfe40e2d02c8980 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,8 @@
+2009-10-16  Benjamin Kosnik  <bkoz@redhat.com>
+
+	* include/c_compatibility/stdatomic.h: Include cstdatomic if
+	__cplusplus.
+
 2009-10-15  Benjamin Kosnik  <bkoz@redhat.com>
 
 	PR libstdc++/40654
diff --git a/libstdc++-v3/include/c_compatibility/stdatomic.h b/libstdc++-v3/include/c_compatibility/stdatomic.h
index f4771166d2b3e98d603797f6a0ed889b3525a9db..eaa45cddac143731f85677ed163113be86c399cd 100644
--- a/libstdc++-v3/include/c_compatibility/stdatomic.h
+++ b/libstdc++-v3/include/c_compatibility/stdatomic.h
@@ -186,8 +186,11 @@ _GLIBCXX_BEGIN_EXTERN_C
 _GLIBCXX_END_EXTERN_C
 _GLIBCXX_END_NAMESPACE
 
-// Inject into global namespace. XXX
-#if defined(__cplusplus) && !defined(_GLIBCXX_STDATOMIC)
+// Inject into global namespace.
+#ifdef __cplusplus
+
+#include <cstdatomic>
+
 using std::memory_order;
 using std::memory_order_relaxed;
 using std::memory_order_consume;
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic_flag/cons/1.cc b/libstdc++-v3/testsuite/29_atomics/atomic_flag/cons/1.cc
new file mode 100644
index 0000000000000000000000000000000000000000..cfb0c1bbb7af64fd9643b7ad1e5f10fe93e7cbc5
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic_flag/cons/1.cc
@@ -0,0 +1,27 @@
+// { dg-options "-std=gnu++0x" }
+// { dg-do compile }
+
+// Copyright (C) 2008, 2009 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <stdatomic.h>
+
+void test01()
+{
+  using namespace std;
+  atomic_flag af = ATOMIC_FLAG_INIT;
+}