diff --git a/ChangeLog b/ChangeLog
index 483ed59a7..f18b49fb7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
 2004-12-08  Alexandre Duret-Lutz  <adl@src.lip6.fr>
 
+	* src/tgbaalgos/replayrun.cc (replay_tgba_run): More comments.
+
 	* src/tgba/tgbaexplicit.cc, src/tgba/tgbaexplicit.hh
 	(tgba_explicit::create_transition(state*, const state*)): New function.
 	* src/tgbaalgos/randomgraph.cc, src/tgbaalgos/randomgraph.hh:
diff --git a/src/tgbaalgos/replayrun.cc b/src/tgbaalgos/replayrun.cc
index 8639e42ee..f86dcc607 100644
--- a/src/tgbaalgos/replayrun.cc
+++ b/src/tgbaalgos/replayrun.cc
@@ -212,6 +212,11 @@ namespace spot
 	delete j;
 
 	// Sum acceptance conditions.
+	//
+	// (Beware l and i designate the next step to consider.
+	// Therefore if i is at the beginning of the cycle, `acc'
+	// contains the acceptance conditions of the last transition
+	// in the prefix; we should not account it.)
 	if (l == &run->cycle && i != l->begin())
 	  {
 	    all_acc |= acc;