diff --git a/tests_with_gitaly/test_commit.py b/tests_with_gitaly/test_commit.py
index 56c348f4bd7d19de694f98cc8b33ca52b7c2140f_dGVzdHNfd2l0aF9naXRhbHkvdGVzdF9jb21taXQucHk=..cbd7927290647a1b9f63ba89bf349ef69d014aab_dGVzdHNfd2l0aF9naXRhbHkvdGVzdF9jb21taXQucHk= 100644
--- a/tests_with_gitaly/test_commit.py
+++ b/tests_with_gitaly/test_commit.py
@@ -8,6 +8,7 @@
 import pytest
 import re
 import time
+from mercurial.node import nullhex as NULL_HEX
 from hgitaly.stub.shared_pb2 import (
     PaginationParameter,
     Repository,
@@ -227,7 +228,7 @@
     mr_ref_path, _ = fixture.write_special_ref(b'merge-requests/2/train',
                                                ctx1.hex())
 
-    assert_compare(revision=b"0000" * 10)
+    assert_compare(revision=NULL_HEX)
     assert_compare(revision=ctx0.hex())
     assert_compare(revision=b'dead' * 10)  # non resolvable full node
     assert_compare(revision=b'branch/default')