diff --git a/tests/base.py b/tests/base.py
index 5a06f85..944af80 100755
--- a/tests/base.py
+++ b/tests/base.py
@@ -902,7 +902,7 @@
     def getPushEvent(self, project, ref, old_rev=None, new_rev=None,
                      added_files=[], removed_files=[], modified_files=[]):
         if not old_rev:
-            old_rev = '00000000000000000000000000000000'
+            old_rev = '0' * 40
         if not new_rev:
             new_rev = random_sha1()
         name = 'push'
diff --git a/tests/unit/test_github_driver.py b/tests/unit/test_github_driver.py
index 4077cca..84fdbde 100644
--- a/tests/unit/test_github_driver.py
+++ b/tests/unit/test_github_driver.py
@@ -110,10 +110,8 @@
 
         build_params = self.builds[0].parameters
         self.assertEqual('refs/tags/newtag', build_params['zuul']['ref'])
-        self.assertEqual('00000000000000000000000000000000',
-                         build_params['zuul']['oldrev'])
+        self.assertFalse('oldrev' in build_params['zuul'])
         self.assertEqual(sha, build_params['zuul']['newrev'])
-
         self.executor_server.hold_jobs_in_build = False
         self.executor_server.release()
         self.waitUntilSettled()