Index: modules/aggregator/aggregator.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/aggregator/aggregator.module,v
retrieving revision 1.374.2.6
diff -u -p -r1.374.2.6 aggregator.module
--- modules/aggregator/aggregator.module	28 May 2010 16:06:59 -0000	1.374.2.6
+++ modules/aggregator/aggregator.module	15 Nov 2010 03:35:55 -0000
@@ -752,7 +752,17 @@ function aggregator_parse_feed(&$data, $
     else {
       $link = $feed['link'];
     }
-    $guid = isset($item['GUID']) ? $item['GUID'] : '';
+
+    // Atom feeds use ID rather than GUID.
+    if (isset($item['GUID'])) {
+      $guid = $item['GUID'];
+    }
+    elseif (isset($item['ID'])) {
+      $guid = $item['ID'];
+    }
+    else {
+      $guid = '';
+    }
 
     // Atom feeds have a CONTENT and/or SUMMARY tag instead of a DESCRIPTION tag.
     if (!empty($item['CONTENT:ENCODED'])) {