diff --git a/conf.py b/conf.py
index 3600585..6e2d2f4 100644
--- a/conf.py
+++ b/conf.py
@@ -42,6 +42,7 @@
     'sphinx.ext.mathjax',
     'sphinxcontrib.bibtex',
     'sphinx.ext.githubpages',
+    'notfound.extension',
 ]
 
 # Add any paths that contain templates here, relative to this directory.
diff --git a/requirements.txt b/requirements.txt
index 6b8a31b..bd413c8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
 sphinx>=5.3.0
 sphinx-rtd-theme>=0.5.2
 sphinxcontrib-bibtex
+sphinx-notfound-page>=1.0.0