diff --git a/templates/lecture.html b/templates/lecture.html
index a5e0a07c6515b8be76e875393441b26ca590aab3..c7d38a3bdf7b8d210fdfb7da9a84a16d36c30199 100644
--- a/templates/lecture.html
+++ b/templates/lecture.html
@@ -13,7 +13,7 @@
 {% block header %}
 {{ super() }}
 
-	<meta property="og:image" content="{{ config.VIDEOPREFIX }}/{{ lecture['titlefile'] }}" />
+	<meta property="og:image" content="{{ config.VIDEOPREFIX }}/thumbnail/l_{{lecture.id}}.jpg" />
 	<meta property="og:title" content="{{ course.title }}: {{ lecture.title}}" />
 	<meta property="og:description" content="{{ lecture.comment }}" />
 {% endblock %}