diff --git a/ChangeLog b/ChangeLog
index 415a81431..27fc4a3d5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2004-11-04  Alexandre Duret-Lutz  <adl@src.lip6.fr>
 
+	* src/tgba/tgba.hh, src/tgba/tgba.cc
+	(tgba::number_of_acceptance_conditions): New method.
+	* src/tgbaalgos/lbtt.cc (lbtt_bfs::lbtt_bfs): Use it.
+
 	* wrap/python/spot.i: Generate bindings for tgbaalgos/dottydec.hh,
 	tgbaalgos/emptiness.hh, tgbaalgos/gtec/gtec.hh, and
 	tgbaalgos/rundotdec.hh.
diff --git a/src/tgba/tgba.cc b/src/tgba/tgba.cc
index 62663d951..b9cb9009a 100644
--- a/src/tgba/tgba.cc
+++ b/src/tgba/tgba.cc
@@ -25,7 +25,8 @@ namespace spot
 {
   tgba::tgba()
     : last_support_conditions_input_(0),
-      last_support_variables_input_(0)
+      last_support_variables_input_(0),
+      num_acc_(-1)
   {
   }
 
@@ -75,4 +76,21 @@ namespace spot
     return "";
   }
 
+  int
+  tgba::number_of_acceptance_conditions() const
+  {
+    if (num_acc_ < 0)
+      {
+	bdd all = all_acceptance_conditions();
+	int n = 0;
+	while (all != bddfalse)
+	  {
+	    ++n;
+	    all -= bdd_satone(all);
+	  }
+	num_acc_ = n;
+      }
+    return num_acc_;
+  }
+
 }
diff --git a/src/tgba/tgba.hh b/src/tgba/tgba.hh
index f9c613a83..ddb9e78ef 100644
--- a/src/tgba/tgba.hh
+++ b/src/tgba/tgba.hh
@@ -173,6 +173,9 @@ namespace spot
     /// the SCC should be equal to the result of this function.
     virtual bdd all_acceptance_conditions() const = 0;
 
+    /// The number of acceptance conditions.
+    virtual int number_of_acceptance_conditions() const;
+
     /// \brief Return the conjuction of all negated acceptance
     /// variables.
     ///
@@ -195,6 +198,7 @@ namespace spot
     mutable bdd last_support_conditions_output_;
     mutable const state* last_support_variables_input_;
     mutable bdd last_support_variables_output_;
+    mutable int num_acc_;
   };
 
 }
diff --git a/src/tgbaalgos/lbtt.cc b/src/tgbaalgos/lbtt.cc
index a172a6e10..59e45a71b 100644
--- a/src/tgbaalgos/lbtt.cc
+++ b/src/tgbaalgos/lbtt.cc
@@ -108,18 +108,9 @@ namespace spot
       lbtt_bfs(const tgba* a, std::ostream& os)
 	: tgba_reachable_iterator_breadth_first(a),
 	  os_(os),
-	  acc_count_(0),
+	  acc_count_(a->number_of_acceptance_conditions()),
 	  acs_(a->all_acceptance_conditions())
-
       {
-	// Count the number of acceptance_conditions.
-	bdd all = a->all_acceptance_conditions();
-	while (all != bddfalse)
-	  {
-	    bdd one = bdd_satone(all);
-	    all -= one;
-	    ++acc_count_;
-	  }
       }
 
       void