diff --git a/index.html b/index.html
index 3b30ed9..45e1467 100644
--- a/index.html
+++ b/index.html
@@ -1,3 +1,5 @@
 <!DOCTYPE html>
+<meta http-equiv="Content-Security-Policy" content="upgrade-insecure-requests">
+
 <title>Puzlet</title>
-<script src="http://puzlet.org/puzlet/js/puzlet.js"></script>
+ <script src="https://puzlet.org/puzlet/js/puzlet.js"></script>
