diff --git a/product/ERP5Type/tests/runFunctionalTest.py b/product/ERP5Type/tests/runFunctionalTest.py
index ecd9e8358eeed6ffb726ab98626a7c2be065ab7d..e7d625c85e620e087800982a5f880ba415ea21bb 100755
--- a/product/ERP5Type/tests/runFunctionalTest.py
+++ b/product/ERP5Type/tests/runFunctionalTest.py
@@ -3,6 +3,7 @@ import os
 import re
 import signal
 import sys
+import shutil
 import getopt
 from time import sleep
 import urllib2
@@ -192,11 +193,16 @@ user_pref("capability.principal.codebase.p1.subjectName", "");""" % \
   pref_file.close()
 
 def runFirefox():
-  os.environ['MOZ_NO_REMOTE'] = '1'
-  if not debug:
+  prepareFirefox()
+  if debug:
+    try:
+      shutil.copy2(os.path.expanduser('~/.Xauthority'), '%s/.Xauthority' % profile_dir)
+    except IOError:
+      pass
+  else:
     os.environ['DISPLAY'] = ':123'
+  os.environ['MOZ_NO_REMOTE'] = '1'
   os.environ['HOME'] = profile_dir
-  prepareFirefox()
   # check if old zelenium or new zelenium
   try:
     urllib2.urlopen("%s/portal_tests/core/scripts/selenium-version.js" % portal_url)