diff --git a/tests/unit/test_cmd.py b/tests/unit/test_cmd.py
index 89b6d76..d6cf973 100644
--- a/tests/unit/test_cmd.py
+++ b/tests/unit/test_cmd.py
@@ -370,8 +370,8 @@ verify_ssl=True"""
                 'project/project1/enqueue',
                 json={'ref': 'refs/heads/stable',
                       'pipeline': 'check',
-                      'oldrev': '0000000000000000000000000000000000000000',
-                      'newrev': '0000000000000000000000000000000000000000'}
+                      'oldrev': None,
+                      'newrev': None}
             )
             self.assertEqual(0, exit_code)
             exit_code = ZC._main(
@@ -387,7 +387,7 @@ verify_ssl=True"""
                 json={'ref': 'refs/heads/stable',
                       'pipeline': 'check',
                       'oldrev': 'ababababab',
-                      'newrev': '0000000000000000000000000000000000000000'}
+                      'newrev': None}
             )
             self.assertEqual(0, exit_code)
             exit_code = ZC._main(
@@ -403,7 +403,7 @@ verify_ssl=True"""
                 json={'ref': 'refs/heads/stable',
                       'pipeline': 'check',
                       'newrev': 'ababababab',
-                      'oldrev': '0000000000000000000000000000000000000000'}
+                      'oldrev': None}
             )
             self.assertEqual(0, exit_code)
             exit_code = ZC._main(
diff --git a/zuulclient/cmd/__init__.py b/zuulclient/cmd/__init__.py
index 6eec0ef..77d7ddc 100644
--- a/zuulclient/cmd/__init__.py
+++ b/zuulclient/cmd/__init__.py
@@ -153,11 +153,6 @@ class ZuulClient():
                 if self.args.oldrev == self.args.newrev:
                     raise ArgumentException(
                         "The old and new revisions must not be the same.")
-            # if they're not set, we pad them out to zero
-            if self.args.oldrev is None:
-                self.args.oldrev = '0000000000000000000000000000000000000000'
-            if self.args.newrev is None:
-                self.args.newrev = '0000000000000000000000000000000000000000'
         if self.args.func == self.dequeue:
             if self.args.change is None and self.args.ref is None:
                 raise ArgumentException("Change or ref needed.")