diff --git a/requirements.txt b/requirements.txt
index f990e42..6ea5f4f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,6 +5,7 @@ Jinja2==2.10.1
 Markdown==3.1.1
 MarkupSafe==1.1.1
 pelican==4.0.1
+pycrypto==2.6.1
 Pygments==2.4.1
 python-dateutil==2.8.0
 pytz==2019.1