diff --git a/ChangeLog b/ChangeLog
index 0ca000c5b..b0b1f8ee0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2009-11-24  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
+
+	Detect running timers, and stop a timer in ltl2tgba.
+
+	* src/misc/timer.hh (time_info::running): New attribute.
+	(time_info::start, time_info::stop): Update and check
+	time_info::running.
+	* src/misc/timer.cc (timer_map::print): Mark running timers with
+	a "+" in the output.
+	* src/tgbatest/ltl2tgba.cc (main): Rename the name of the timers
+	for SCC and simulation reduction, and actually stop the SCC timer.
+
 2009-11-23  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
 
 	* src/tgbaalgos/sccfilter.cc (create_transition): Do not clone
diff --git a/src/misc/timer.cc b/src/misc/timer.cc
index 719f0b3a0..21142299c 100644
--- a/src/misc/timer.cc
+++ b/src/misc/timer.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2004, 2005  Laboratoire d'Informatique de Paris 6 (LIP6),
+// Copyright (C) 2004, 2005, 2009  Laboratoire d'Informatique de Paris 6 (LIP6),
 // département Systèmes Répartis Coopératifs (SRC), Université Pierre
 // et Marie Curie.
 //
@@ -56,20 +56,22 @@ namespace spot
 	  name.erase(22);
 
 	const spot::timer& t = i->second.first;
-	os << std::setw(22) << name << " |"
+	const char* sep = t.is_running() ? "+|" : " |";
+
+	os << std::setw(22) << name << sep
 	   << std::setw(6) << t.utime() << " "
 	   << std::setw(8) << (total.utime ?
 			       100.0 * t.utime() / total.utime : 0.)
-	   << " |"
+	   << sep
 	   << std::setw(6) << t.stime() << " "
 	   << std::setw(8) << (total.stime ?
 			       100.0 * t.stime() / total.stime : 0.)
-	   << " |"
+	   << sep
 	   << std::setw(6) << t.utime() + t.stime() << " "
 	   << std::setw(8) << (grand_total ?
 			       (100.0 * (t.utime() + t.stime()) /
 				grand_total) : 0.)
-	   << " |"
+	   << sep
 	   << std::setw(4) << i->second.second
 	   << std::endl;
       }
diff --git a/src/misc/timer.hh b/src/misc/timer.hh
index 974fbd19d..96b8ed13a 100644
--- a/src/misc/timer.hh
+++ b/src/misc/timer.hh
@@ -1,4 +1,4 @@
-// Copyright (C) 2004  Laboratoire d'Informatique de Paris 6 (LIP6),
+// Copyright (C) 2004, 2009  Laboratoire d'Informatique de Paris 6 (LIP6),
 // département Systèmes Répartis Coopératifs (SRC), Université Pierre
 // et Marie Curie.
 //
@@ -53,6 +53,8 @@ namespace spot
     void
     start()
     {
+      assert(!running);
+      running = true;
       struct tms tmp;
       times(&tmp);
       start_.utime = tmp.tms_utime;
@@ -67,6 +69,8 @@ namespace spot
       times(&tmp);
       total_.utime += tmp.tms_utime - start_.utime;
       total_.stime += tmp.tms_stime - start_.stime;
+      assert(running);
+      running = false;
     }
 
     /// \brief Return the user time of all accumulated interval.
@@ -89,9 +93,18 @@ namespace spot
       return total_.stime;
     }
 
+
+    /// \brief Whether the timer is running.
+    bool
+    is_running() const
+    {
+      return running;
+    }
+
   protected:
     time_info start_;
     time_info total_;
+    bool running;
   };
 
   /// \brief A map of timer, where each timer has a name.
diff --git a/src/tgbatest/ltl2tgba.cc b/src/tgbatest/ltl2tgba.cc
index 7b7501898..d7c5340df 100644
--- a/src/tgbatest/ltl2tgba.cc
+++ b/src/tgbatest/ltl2tgba.cc
@@ -722,14 +722,14 @@ main(int argc, char** argv)
 
 	  if (reduc_aut & spot::Reduce_Scc)
 	    {
-	      tm.start("reducing formula aut. w/ SCC");
+	      tm.start("reducing A_f w/ SCC");
 	      a = aut_scc = spot::scc_filter(a);
-	      tm.start("reducing formula aut. w/ SCC");
+	      tm.start("reducing A_f w/ SCC");
 	    }
 
 	  if (reduc_aut & !spot::Reduce_Scc)
 	    {
-	      tm.start("reducing formula aut. w/ sim.");
+	      tm.start("reducing A_f w/ sim.");
 	      a = aut_red = new spot::tgba_reduc(a);
 
 	      if (reduc_aut & (spot::Reduce_quotient_Dir_Sim |
@@ -779,7 +779,7 @@ main(int argc, char** argv)
 		  if (rel_del)
 		    spot::free_relation_simulation(rel_del);
 		}
-	      tm.stop("reducing formula aut. w/ sim.");
+	      tm.stop("reducing A_f w/ sim.");
 	    }
 	}