diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7cde0c4e..7ee7a484 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 - Fixed a bug that export an empty maintenance report would crash.
+- Fixed another bug that maintenance report could have an invalid `last_updated_by` value.
 
 ## [2.3.1] - 2019-10-03
 
diff --git a/pubtools/pulplib/_impl/model/maintenance.py b/pubtools/pulplib/_impl/model/maintenance.py
index 8df8e5b0..89c6e29f 100644
--- a/pubtools/pulplib/_impl/model/maintenance.py
+++ b/pubtools/pulplib/_impl/model/maintenance.py
@@ -122,7 +122,7 @@ def _export_dict(self):
         """export a raw dictionary of maintenance report"""
         report = {
             "last_updated": write_timestamp(self.last_updated),
-            "last_updated_by": self.last_updated_by,
+            "last_updated_by": self.last_updated_by or self._OWNER,
             "repos": {},
         }
 
diff --git a/tests/maintenance/test_maintenance.py b/tests/maintenance/test_maintenance.py
index 95f47ac4..cd8396df 100644
--- a/tests/maintenance/test_maintenance.py
+++ b/tests/maintenance/test_maintenance.py
@@ -103,3 +103,5 @@ def test_export_empty_report():
     data = report._export_dict()
     # exported report should have a timestamp
     assert datetime.datetime.strptime(data["last_updated"], "%Y-%m-%dT%H:%M:%SZ")
+    # exported report should have the default owner
+    assert data["last_updated_by"] == "ContentDelivery"