diff -uNr feeds.orig/libraries/common_syndication_parser.inc feeds/libraries/common_syndication_parser.inc
--- feeds.orig/libraries/common_syndication_parser.inc	2010-03-29 01:33:22.000000000 +0100
+++ feeds/libraries/common_syndication_parser.inc	2010-04-20 09:47:22.000000000 +0100
@@ -392,7 +392,9 @@
     }
 
     if (isset($news['guid'])) {
-      $guid = "{$news['guid']}";
+      if (strlen($news['guid']) > 0) {
+        $guid = "{$news['guid']}";
+      }
     }
 
     $additional_taxonomies = array();