diff --git a/ChangeLog b/ChangeLog
index 1a175b010..514f8ccfc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2005-02-04  Alexandre Duret-Lutz  <adl@src.lip6.fr>
+
+	* src/tgbaalgos/emptiness_stats.hh (unsigned_statistics::stats_map_):
+	Use char* for keys, not std::string.
+
 2005-02-03  Alexandre Duret-Lutz  <adl@src.lip6.fr>
 
 	* tgbaalgos/emptiness_stats.hh (unsigned_statistics): New base
diff --git a/src/tgbaalgos/emptiness_stats.hh b/src/tgbaalgos/emptiness_stats.hh
index 78e1468fd..324b73c9e 100644
--- a/src/tgbaalgos/emptiness_stats.hh
+++ b/src/tgbaalgos/emptiness_stats.hh
@@ -24,7 +24,6 @@
 
 #include <cassert>
 #include <map>
-#include <string>
 
 namespace spot
 {
@@ -51,7 +50,7 @@ namespace spot
 
   protected:
     typedef unsigned (unsigned_statistics::*unsigned_fun_)() const;
-    typedef std::map<std::string, unsigned_fun_> stats_map_;
+    typedef std::map<const char*, unsigned_fun_> stats_map_;
     stats_map_ stats_;
   };