diff --git a/tests/core/optba.test b/tests/core/optba.test
index b4863fc6e..6a8817c56 100755
--- a/tests/core/optba.test
+++ b/tests/core/optba.test
@@ -1,7 +1,7 @@
 #!/bin/sh
 # -*- coding: utf-8 -*-
-# Copyright (C) 2015 Laboratoire de Recherche et Développement de
-# l'Epita (LRDE).
+# Copyright (C) 2015, 2017 Laboratoire de Recherche et Développement
+# de l'Epita (LRDE).
 #
 # This file is part of Spot, a model checking library.
 #
@@ -19,6 +19,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 . ./defs
+set -x
 
 # This is a case where autfilt is used to optimize BA, but used to
 # produce a larger one.   See issue #79.