diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..0842e6c
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+/src/extra_mailman_archivers.egg-info/
+__pycache__/
diff --git a/setup.cfg b/setup.cfg
index 8407662..a9085fe 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -18,6 +18,8 @@ package_dir =
     = src
 packages = find:
 python_requires = >=3.5
+install_requires =
+    mailman >=3.2.1
 
 [options.packages.find]
 where = src
diff --git a/src/extra_mailman_archivers/monthly_archiver.py b/src/extra_mailman_archivers/monthly_archiver.py
index b601f48..0a63513 100644
--- a/src/extra_mailman_archivers/monthly_archiver.py
+++ b/src/extra_mailman_archivers/monthly_archiver.py
@@ -25,16 +25,12 @@ month.
 """
 
 from contextlib import suppress
-import datetime
-from datetime import timedelta
 from email.utils import parsedate
 import gzip
 import logging
 import os
 import time
 
-from flufl.lock import Lock, TimeOutError
-from mailbox import Maildir
 from mailman.config import config
 from mailman.interfaces.archiver import IArchiver
 from public import public