--- a/config/tests/unit-nsinstall.py
+++ b/config/tests/unit-nsinstall.py
@@ -163,17 +163,17 @@ class TestNsinstall(unittest.TestCase):
             testdir = self.mkdirs(u"\u4241\u1D04\u1414")
             # We don't use subprocess because it can't handle Unicode on
             # Windows <http://bugs.python.org/issue1759845>. mozprocess calls
             # CreateProcessW directly so it's perfect.
             p = processhandler.ProcessHandlerMixin([sys.executable,
                                                     NSINSTALL_PATH,
                                                     testfile, testdir])
             p.run()
-            rv = p.waitForFinish()
+            rv = p.wait()
 
             self.assertEqual(rv, 0)
             destfile = os.path.join(testdir, filename)
             self.assert_(os.path.isfile(destfile))
 
     # TODO: implement -R, -l, -L and test them!