diff --git a/ChangeLog b/ChangeLog
index 6ec4456a9..60f55035e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2005-09-05  Heikki Tauriainen  <heikki.tauriainen@tkk.fi>
+
+	* src/ltlast/visitor.hh (visitor, const_visitor): Add empty
+	virtual destructors.
+	* src/tgba/tgbabddfactory.hh (tgba_bdd_factory): Likewise.
+	* src/misc/hash.hh: Use the std namespace only with GCC 3.0,
+	not with all compiler versions with minor version 0.
+	* src/tgba/tgbatba.cc (tgba_tba_proxy_succ_iterator): Fix
+	friend declaration of ::spot::tgba_tba_proxy.
+
 2005-09-01  Alexandre Duret-Lutz  <adl@src.lip6.fr>
 
 	* src/tgbaalgos/magic.hh: \fixme is not a doxygen command.  Use \bug.
diff --git a/src/ltlast/visitor.hh b/src/ltlast/visitor.hh
index 0cbf6d45d..a6cfb933b 100644
--- a/src/ltlast/visitor.hh
+++ b/src/ltlast/visitor.hh
@@ -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.
 //
@@ -41,6 +41,7 @@ namespace spot
     /// spot::ltl:const_visitor instead.
     struct visitor
     {
+      virtual ~visitor() {}
       virtual void visit(atomic_prop* node) = 0;
       virtual void visit(constant* node) = 0;
       virtual void visit(binop* node) = 0;
@@ -58,6 +59,7 @@ namespace spot
     /// spot::ltl:visitor instead.
     struct const_visitor
     {
+      virtual ~const_visitor() {}
       virtual void visit(const atomic_prop* node) = 0;
       virtual void visit(const constant* node) = 0;
       virtual void visit(const binop* node) = 0;
diff --git a/src/misc/hash.hh b/src/misc/hash.hh
index e1562ec1b..b47cab6ae 100644
--- a/src/misc/hash.hh
+++ b/src/misc/hash.hh
@@ -40,7 +40,7 @@
 #  else
 #    include <ext/hash_map>
 #    include <ext/hash_set>
-#    if __GNUC_MINOR__ == 0
+#    if __GNUC__ == 3 && __GNUC_MINOR__ == 0
       namespace Sgi = std;               // GCC 3.0
 #    else
       namespace Sgi = ::__gnu_cxx;       // GCC 3.1 and later
diff --git a/src/tgba/tgbabddfactory.hh b/src/tgba/tgbabddfactory.hh
index 18d7c45c5..a4b609dc7 100644
--- a/src/tgba/tgbabddfactory.hh
+++ b/src/tgba/tgbabddfactory.hh
@@ -33,6 +33,7 @@ namespace spot
   class tgba_bdd_factory
   {
   public:
+    virtual ~tgba_bdd_factory() {}
     /// Get the core data for the new automata.
     virtual const tgba_bdd_core_data& get_core_data() const = 0;
   };
diff --git a/src/tgba/tgbatba.cc b/src/tgba/tgbatba.cc
index 04cc0bbff..575b3731d 100644
--- a/src/tgba/tgbatba.cc
+++ b/src/tgba/tgbatba.cc
@@ -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.
 //
@@ -226,7 +226,7 @@ namespace spot
       bool accepting_;
       const list& cycle_;
       const bdd the_acceptance_cond_;
-      friend class tgba_tba_proxy;
+      friend class ::spot::tgba_tba_proxy;
     };
 
   } // anonymous