diff --git a/setup.py b/setup.py
index ee681bb0d517cb71312304c05ef823efaaf85b4b..51447363201fb9f886b2edc0ce2076098fe612de 100755
--- a/setup.py
+++ b/setup.py
@@ -17,6 +17,7 @@ setup(
         # 1.4.1 crashes when trying to save some documents.
         'odfpy>=1.4.0,!=1.4.1',  # Debian:python3-odf
         'pdfminer.six>=20200101',
+        'python-dateutil>=2.7',  # Debian:python3-dateutil
         'PyYAML>=3.0',  # Debian:python3-yaml
         'regex',  # Debian:python3-regex
         'rt>=2.0',