diff --git a/swh/storage/tests/test_storage.py b/swh/storage/tests/test_storage.py
--- a/swh/storage/tests/test_storage.py
+++ b/swh/storage/tests/test_storage.py
@@ -104,7 +104,7 @@
     round-trip through a DB (eg. Cassandra)
 
     """
-    return date.replace(microsecond=round(date.microsecond, -3))
+    return date.replace(microsecond=date.microsecond // 1000000)
 
 
 class LazyContent(Content):