diff --git a/product/ERP5Type/tests/ERP5TypeFunctionalTestCase.py b/product/ERP5Type/tests/ERP5TypeFunctionalTestCase.py
index 489dda548ccca47e6b670a5bc06a3908c9887de6..28f0c884ecc02f78bb8df51eb8ad2fe68a92d7e8 100644
--- a/product/ERP5Type/tests/ERP5TypeFunctionalTestCase.py
+++ b/product/ERP5Type/tests/ERP5TypeFunctionalTestCase.py
@@ -108,9 +108,8 @@ class Xvfb(Process):
 
   def run(self):
     for display_try in self.display_list:
-      lock_filepath = '/tmp/.X%s-lock' % display_try.replace(":", "")
-      if not os.path.exists(lock_filepath):
-        self._runCommand(display_try)
+      self._runCommand(display_try)
+      if self.process.poll() is None:
         self.display = display_try
         os.environ['DISPLAY'] = self.display
         break