diff --git a/ereuse_devicehub/resources/tradedocument/models.py b/ereuse_devicehub/resources/tradedocument/models.py
index 7f211637..07af62d1 100644
--- a/ereuse_devicehub/resources/tradedocument/models.py
+++ b/ereuse_devicehub/resources/tradedocument/models.py
@@ -172,7 +172,9 @@ class TradeDocument(Thing):
         return sorted(ev for ev in actions if ev.severity >= Severity.Warning)
 
     def __lt__(self, other):
-        return self.id < other.id
+        if self.id and other.id:
+            return self.id < other.id
+        return False
 
     def __str__(self) -> str:
         return '{0.file_name}'.format(self)
diff --git a/tests/test_render_2_0.py b/tests/test_render_2_0.py
index fbd437d9..f9f2299e 100644
--- a/tests/test_render_2_0.py
+++ b/tests/test_render_2_0.py
@@ -2470,6 +2470,7 @@ def test_bug_3831_documents(user3: UserClientFlask):
     assert 'Delete Lot' in body
     assert 'Incoming Lot' in body
 
+    lot_id = Lot.query.all()[1].id
     uri = f'/inventory/lot/{lot_id}/trade-document/add/'
     body, status = user3.get(uri)
 
@@ -2487,8 +2488,16 @@ def test_bug_3831_documents(user3: UserClientFlask):
     }
 
     uri = f'/inventory/lot/{lot_id}/trade-document/add/'
-    # body, status = user3.post(uri, data=data, content_type="multipart/form-data")
-    # assert status == '200 OK'
+    body, status = user3.post(uri, data=data, content_type="multipart/form-data")
+    assert status == '200 OK'
+
+    # Second document
+    uri = f'/inventory/lot/{lot_id}/trade-document/add/'
+    file_upload = (BytesIO(b_file), file_name)
+    data['file'] = file_upload
+    data['csrf_token'] = generate_csrf()
+    body, status = user3.post(uri, data=data, content_type="multipart/form-data")
+    assert status == '200 OK'
 
 
 @pytest.mark.mvp