diff --git a/lib/template.html b/lib/template.html
index 981aa9a..512ad5a 100755
--- a/lib/template.html
+++ b/lib/template.html
@@ -50,6 +50,10 @@
   <meta property="og:type" content="website" />
 {% endif %}
 
+{% if page.last_modified_at %}
+  <meta property="article:modified_time" content="{{ page.last_modified_at | date_to_xmlschema }}" />
+{% endif %}
+
 {% if paginator.previous_page %}
   <link rel="prev" href="{{ paginator.previous_page_path | absolute_url }}" />
 {% endif %}