diff --git a/swh/indexer/tests/test_origin_head.py b/swh/indexer/tests/test_origin_head.py
--- a/swh/indexer/tests/test_origin_head.py
+++ b/swh/indexer/tests/test_origin_head.py
@@ -4,6 +4,7 @@
 # See top-level LICENSE file for more information
 
 import unittest
+from datetime import datetime
 
 from swh.indexer.origin_head import OriginHeadIndexer
 from swh.indexer.tests.utils import (
@@ -56,7 +57,7 @@
             'url': origin_url,
         })
         visit = self.indexer.storage.origin_visit_add(
-            origin_url, '2019-02-27', type='git',
+            origin_url, datetime(2019, 2, 27), type='git',
         )
         self.indexer.storage.snapshot_add([{
             'id': b'foo',
@@ -87,7 +88,7 @@
             'url': origin_url,
         })
         visit = self.indexer.storage.origin_visit_add(
-            origin_url, '2019-02-27', type='pypi')
+            origin_url, datetime(2019, 2, 27), type='pypi')
         self.indexer.storage.snapshot_add([{
             'id': b'foo',
             'branches': {
diff --git a/swh/indexer/tests/utils.py b/swh/indexer/tests/utils.py
--- a/swh/indexer/tests/utils.py
+++ b/swh/indexer/tests/utils.py
@@ -159,7 +159,7 @@
 
 REVISIONS = [{
     'id': hash_to_bytes('8dbb6aeb036e7fd80664eb8bfd1507881af1ba9f'),
-    'message': 'Improve search functionality',
+    'message': b'Improve search functionality',
     'author': {
         'name': b'Andrew Nesbitt',
         'fullname': b'Andrew Nesbitt <andrewnez@gmail.com>',
@@ -171,11 +171,11 @@
         'email': b'andrewnez@gmail.com'
     },
     'committer_date': {
-        'negative_utc': None,
+        'negative_utc': False,
         'offset': 120,
         'timestamp': {
             'microseconds': 0,
-            'seconds': 1380883849
+            'seconds': 1380883849,
         }
     },
     'type': 'git',
@@ -184,7 +184,7 @@
         'negative_utc': False,
         'timestamp': {
             'seconds': 1487596456,
-            'microseconds': 0
+            'microseconds': 0,
         },
         'offset': 0
     },