diff --git a/lectures/_config.yml b/lectures/_config.yml
index f21cabf0..bc628f10 100644
--- a/lectures/_config.yml
+++ b/lectures/_config.yml
@@ -49,7 +49,7 @@ sphinx:
         SVG:
           scale: 0.92,
           useGlobalCache: true
-    mathjax_path: https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.7/MathJax.js?config=TeX-MML-AM_CHTML
+    mathjax_path: https://cdn.jsdelivr.net/npm/mathjax@2.7.9/MathJax.js?config=TeX-MML-AM_CHTML
     tojupyter_static_file_path: ["_static"]
     tojupyter_target_html: true
     tojupyter_urlpath: "https://datascience.quantecon.org/"