diff --git a/_includes/head.html b/_includes/head.html
index 6b694d2..40d96ae 100644
--- a/_includes/head.html
+++ b/_includes/head.html
@@ -13,4 +13,5 @@
   <link rel="alternate" type="application/rss+xml" title="{{ site.title }} - Suomeksi" href="{{ "/blog/feed.fi.xml" | prepend: site.baseurl | prepend: site.url }}" />
  <!-- Help http://validator-search.verisignlabs.com/ -->
  <link rel="prefetch" href="https://prefetch.validatorsearch.verisignlabs.com" />
+  <meta http-equiv="Content-Security-Policy" content="upgrade-insecure-requests">
 </head>