diff --git a/exploring-numpy-godber/reveal.js/package.json b/exploring-numpy-godber/reveal.js/package.json
index 5debdd2..835c792 100644
--- a/exploring-numpy-godber/reveal.js/package.json
+++ b/exploring-numpy-godber/reveal.js/package.json
@@ -22,7 +22,7 @@
   },
   "dependencies": {
     "underscore": "~1.5.1",
-    "express": "~2.5.9",
+    "express": "~4.17.1",
     "mustache": "~0.7.2",
     "socket.io": "~0.9.13"
   },