diff --git a/requirements.txt b/requirements.txt
index bbbfd3c..c6a0917 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,6 +6,7 @@ feedgenerator==1.9
 html5validator==0.3.1
 Jinja2==2.10
 Markdown==3.1
+markdown-extra==1.0.1
 MarkupSafe==1.1.0
 pelican==4.0.1
 Pygments==2.3.1