diff --git a/ChangeLog b/ChangeLog
index 07938b241..5250db7dc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2010-04-13  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
+
+	Fix bugs in minimize(), caught by spotlbtt.test.
+
+	* src/tgbaalgos/minimize.cc (minimize): Don't add acceptance
+	conditions if the final set is empty.
+	* src/tgbaalgos/powerset.cc (tgba_powerset): Add the initial state
+	to acc_list if it is accepting.  Also do not compute an SCC build
+	map if we don't have to build acc_list.
+
 2010-04-13  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
 
 	"ltl2tgba -Rm" will apply WDBA-minimization only if correct.
diff --git a/src/tgbaalgos/minimize.cc b/src/tgbaalgos/minimize.cc
index a2c5cfa32..f986d17dc 100644
--- a/src/tgbaalgos/minimize.cc
+++ b/src/tgbaalgos/minimize.cc
@@ -93,7 +93,8 @@ namespace spot
     tgba_explicit_number* res = new tgba_explicit_number(a->get_dict());
     // For each transition in the initial automaton, add the corresponding
     // transition in res.
-    res->declare_acceptance_condition(ltl::constant::true_instance());
+    if (!final->empty())
+      res->declare_acceptance_condition(ltl::constant::true_instance());
     for (sit = sets.begin(); sit != sets.end(); ++sit)
     {
       hash_set::iterator hit;
diff --git a/src/tgbaalgos/powerset.cc b/src/tgbaalgos/powerset.cc
index 4fd0408cb..3dff3f6f4 100644
--- a/src/tgbaalgos/powerset.cc
+++ b/src/tgbaalgos/powerset.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2009 Laboratoire de Recherche et Développement
+// Copyright (C) 2009, 2010 Laboratoire de Recherche et Développement
 // de l'Epita (LRDE).
 // Copyright (C) 2004 Laboratoire d'Informatique de Paris 6 (LIP6),
 // département Systèmes Répartis Coopératifs (SRC), Université Pierre
@@ -56,7 +56,12 @@ namespace spot
       ps.insert(s);
       todo.push_back(ps);
       seen[ps] = 1;
-      m.build_map();
+      if (acc_list)
+	{
+	  m.build_map();
+	  if (m.accepting(m.scc_of_state(s)))
+	    acc_list->push_front(new state_explicit(res->add_state(1)));
+	}
     }
 
     unsigned state_num = 1;
@@ -99,9 +104,12 @@ namespace spot
 			{
 			  states.insert(s);
 			}
-                      unsigned scc_num = m.scc_of_state(s);
-                      if (m.accepting(scc_num))
-                        accepting = true;
+		      if (acc_list)
+			{
+			  unsigned scc_num = m.scc_of_state(s);
+			  if (m.accepting(scc_num))
+			    accepting = true;
+			}
 		      dest.insert(s);
 		    }
 		delete si;
@@ -123,7 +131,7 @@ namespace spot
 		seen[dest] = dest_num;
 		todo.push_back(dest);
                 t = res->create_transition(seen[src], dest_num);
-                if (acc_list && accepting)
+                if (accepting)
                 {
                   const state* dst = new state_explicit(t->dest);
                   acc_list->push_front(dst);
diff --git a/src/tgbatest/minimize.cc b/src/tgbatest/minimize.cc
index 5f193de42..4008fe1a1 100644
--- a/src/tgbatest/minimize.cc
+++ b/src/tgbatest/minimize.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2010 Laboratoire de Recherche et Développement
+// Copyright (C) 2010 Laboratoire de Recherche et Développement
 // de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.