diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 235aa0578d4..92fe3827e1b 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,11 @@
+2011-11-19  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	* include/debug/bitset (operator[](size_t) const): Declare constexpr.
+	* include/profile/bitset: Likewise.
+	* testsuite/23_containers/bitset/operations/constexpr.cc: Split out
+	non portable bits to...
+	* testsuite/23_containers/bitset/operations/constexpr-2.cc: ... here.
+
 2011-11-18  Harti Brandt  <hartmut.brandt@dlr.de>
 
 	PR libstdc++/51209
diff --git a/libstdc++-v3/include/debug/bitset b/libstdc++-v3/include/debug/bitset
index f44bbcddefd..3d865c1c1c2 100644
--- a/libstdc++-v3/include/debug/bitset
+++ b/libstdc++-v3/include/debug/bitset
@@ -51,7 +51,7 @@ namespace __debug
     public:
       // In C++0x we rely on normal reference type to preserve the property
       // of bitset to be use as a literal.
-      // TODO: Find an other solution.
+      // TODO: Find another solution.
 #ifdef __GXX_EXPERIMENTAL_CXX0X__
       typedef typename _Base::reference reference;
 #else
@@ -272,11 +272,14 @@ namespace __debug
 
       // _GLIBCXX_RESOLVE_LIB_DEFECTS
       // 11. Bitset minor problems
-      bool
+      _GLIBCXX_CONSTEXPR bool
       operator[](size_t __pos) const
       {
+#ifndef __GXX_EXPERIMENTAL_CXX0X__
+	// TODO: Check in debug-mode too.
 	__glibcxx_check_subscript(__pos);
-	return _M_base()[__pos];
+#endif
+	return _Base::operator[](__pos);
       }
 
       using _Base::to_ulong;
diff --git a/libstdc++-v3/include/profile/bitset b/libstdc++-v3/include/profile/bitset
index a2cba5efe80..17ee49b5a60 100644
--- a/libstdc++-v3/include/profile/bitset
+++ b/libstdc++-v3/include/profile/bitset
@@ -232,10 +232,10 @@ namespace __profile
 
       // _GLIBCXX_RESOLVE_LIB_DEFECTS
       // 11. Bitset minor problems
-      bool
+      _GLIBCXX_CONSTEXPR bool
       operator[](size_t __pos) const
       {
-	return _M_base()[__pos];
+	return _Base::operator[](__pos);
       }
 
       using _Base::to_ulong;
diff --git a/libstdc++-v3/testsuite/23_containers/bitset/operations/constexpr-2.cc b/libstdc++-v3/testsuite/23_containers/bitset/operations/constexpr-2.cc
new file mode 100644
index 00000000000..14ab8e71275
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/bitset/operations/constexpr-2.cc
@@ -0,0 +1,36 @@
+// { dg-do compile }
+// { dg-require-normal-mode "" }
+// { dg-options "-std=gnu++0x" }
+
+// Copyright (C) 2011 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 <bitset>
+
+int main()
+{
+  // bitset base type
+  typedef std::_Base_bitset<6> bitset_base;
+  constexpr bitset_base base = bitset_base();
+
+  constexpr auto r1 __attribute__((unused)) = base._M_getword(2);
+  // constexpr auto r2 = base._M_getdata(); // error, pointer to this
+  auto r2 __attribute__((unused)) = base._M_getdata(); 
+  constexpr auto r3 __attribute__((unused)) = base._M_hiword();
+
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/23_containers/bitset/operations/constexpr.cc b/libstdc++-v3/testsuite/23_containers/bitset/operations/constexpr.cc
index fc171c8238f..384f01a5dff 100644
--- a/libstdc++-v3/testsuite/23_containers/bitset/operations/constexpr.cc
+++ b/libstdc++-v3/testsuite/23_containers/bitset/operations/constexpr.cc
@@ -22,15 +22,6 @@
 
 int main()
 {
-  // bitset base type
-  typedef std::_Base_bitset<6> bitset_base;
-  constexpr bitset_base base = bitset_base();
-
-  constexpr auto r1 __attribute__((unused)) = base._M_getword(2);
-  // constexpr auto r2 = base._M_getdata(); // error, pointer to this
-  auto r2 __attribute__((unused)) = base._M_getdata(); 
-  constexpr auto r3 __attribute__((unused)) = base._M_hiword();
-
   // bitset operators
   typedef std::bitset<6> bitset_type;
   constexpr bitset_type a = bitset_type();