diff --git a/site/plugins/feed/template.php b/site/plugins/feed/template.php
index 8054947..d126425 100644
--- a/site/plugins/feed/template.php
+++ b/site/plugins/feed/template.php
@@ -5,7 +5,7 @@
     <title><?php echo xml($title) ?></title>
     <link><?php echo xml($link) ?></link>
     <generator><?php echo c::get('feed.generator', 'Kirby') ?></generator>
-    <lastBuildDate><?php echo date('r', $modified) ?></lastBuildDate>
+    <lastBuildDate><?php echo date('r', strtotime($modified)) ?></lastBuildDate>
     <atom:link href="<?php echo xml($url) ?>" rel="self" type="application/rss+xml" />
 
     <?php if(!empty($description)): ?>