diff --git a/mkdocs.yml b/mkdocs.yml
index c31cee31..620b9fe7 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -36,7 +36,7 @@ markdown_extensions:
 repo_url: https://github.com/hackingmaterials/matbench
 
 extra_javascript:
-  - https://polyfill.io/v3/polyfill.min.js?features=es6
+  - https://cdnjs.cloudflare.com/polyfill/v3/polyfill.min.js?features=es6
   - https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js
 
 extra_css: