diff --git a/modules/node/node.module b/modules/node/node.module
index 8f247cd..fca1ba8 100644
--- a/modules/node/node.module
+++ b/modules/node/node.module
@@ -2643,6 +2643,9 @@ function node_feed($nids = FALSE, $channel = array()) {
   $output .= format_rss_channel($channel['title'], $channel['link'], $channel['description'], $items, $channel['language'], $channel_extras);
   $output .= "</rss>\n";
 
+  // Set the Last-Modified header to the creation date of the first node
+  drupal_add_http_header('Last-Modified', gmdate(DATE_RFC2822, reset($nodes)->created));
+  
   drupal_add_http_header('Content-Type', 'application/rss+xml; charset=utf-8');
   print $output;
 }