diff --git a/demo/index.html b/demo/index.html
index 9a0314d..708efdb 100644
--- a/demo/index.html
+++ b/demo/index.html
@@ -17,7 +17,7 @@
 
 <p>
     A 10,000-point demo of <a href="https://github.com/Leaflet/Leaflet.heat">Leaflet.heat</a>, a tiny and fast Leaflet heatmap plugin.
-    <iframe class="ghbtns" src="http://ghbtns.com/github-btn.html?user=Leaflet&amp;repo=Leaflet.heat&amp;type=watch&amp;count=true"
+    <iframe class="ghbtns" src="https://ghbtns.com/github-btn.html?user=Leaflet&amp;repo=Leaflet.heat&amp;type=watch&amp;count=true"
   allowtransparency="true" frameborder="0" scrolling="0" width="90" height="20"></iframe>
 </p>
 
@@ -28,13 +28,13 @@
 
 <script src="../dist/leaflet-heat.js"></script>
 
-<script src="http://leaflet.github.io/Leaflet.markercluster/example/realworld.10000.js"></script>
+<script src="https://leaflet.github.io/Leaflet.markercluster/example/realworld.10000.js"></script>
 <script>
 
 var map = L.map('map').setView([-37.87, 175.475], 12);
 
 var tiles = L.tileLayer('https://tile.openstreetmap.org/{z}/{x}/{y}.png', {
-    attribution: '&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors',
+    attribution: '&copy; <a href="https://osm.org/copyright">OpenStreetMap</a> contributors',
 }).addTo(map);
 
 addressPoints = addressPoints.map(function (p) { return [p[0], p[1]]; });