diff --git a/ChangeLog b/ChangeLog
index 514f8ccfc..fc1664658 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2005-02-04  Alexandre Duret-Lutz  <adl@src.lip6.fr>
 
+	* src/misc/ltstr.hh: New file.
+	* src/misc/Makefile.am (misc_HEADERS): Add it.
+
 	* src/tgbaalgos/emptiness_stats.hh (unsigned_statistics::stats_map_):
 	Use char* for keys, not std::string.
 
diff --git a/src/misc/Makefile.am b/src/misc/Makefile.am
index 718071e94..40ff214ae 100644
--- a/src/misc/Makefile.am
+++ b/src/misc/Makefile.am
@@ -1,4 +1,4 @@
-## Copyright (C) 2003, 2004  Laboratoire d'Informatique de Paris 6 (LIP6),
+## Copyright (C) 2003, 2004, 2005  Laboratoire d'Informatique de Paris 6 (LIP6),
 ## département Systèmes Répartis Coopératifs (SRC), Université Pierre
 ## et Marie Curie.
 ##
@@ -32,6 +32,7 @@ misc_HEADERS = \
   freelist.hh \
   hash.hh \
   hashfunc.hh \
+  ltstr.hh \
   minato.hh \
   modgray.hh \
   random.hh \
diff --git a/src/misc/ltstr.hh b/src/misc/ltstr.hh
new file mode 100644
index 000000000..02f398d8c
--- /dev/null
+++ b/src/misc/ltstr.hh
@@ -0,0 +1,52 @@
+// Copyright (C) 2005  Laboratoire d'Informatique de Paris 6 (LIP6),
+// département Systèmes Répartis Coopératifs (SRC), Université Pierre
+// et Marie Curie.
+//
+// This file is part of Spot, a model checking library.
+//
+// Spot 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 2 of the License, or
+// (at your option) any later version.
+//
+// Spot 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 Spot; see the file COPYING.  If not, write to the Free
+// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+// 02111-1307, USA.
+
+#ifndef SPOT_MISC_LTSTR_HH
+#  define SPOT_MISC_LTSTR_HH
+
+#include <cstring>
+
+namespace spot
+{
+
+  /// \brief Strict Weak Ordering for \c char*.
+  /// \ingroup misc_tools
+  ///
+  /// This is meant to be used as a comparison functor for
+  /// STL \c map whose key are of type <code>const char*</code>.
+  ///
+  /// For instance here is how one could declare
+  /// a map of <code>const state*</code>.
+  /// \code
+  ///   std::map<const char*, int, spot::state_ptr_less_than> seen;
+  /// \endcode
+  struct char_ptr_less_than:
+    public std::binary_function<const char*, const char*, bool>
+  {
+    bool
+    operator()(const char* left, const char* right) const
+    {
+      return strcmp(left, right) < 0;
+    }
+  };
+}
+
+#endif // SPOT_MISC_LTSTR_HH