--- test_mailbox.py.orig	2006-12-17 17:32:48.000000000 +0000
+++ test_mailbox.py	2006-12-20 17:47:38.000000000 +0000
@@ -464,7 +464,9 @@
         os.wait()
 
         # We expect the mailbox to contain 50 messages.
+        self._box.lock()
         self.assert_(len(self._box) == 50)
+        self._box.unlock()
 
     def _get_lock_path(self):
         # Return the path of the dot lock file. May be overridden.