diff --git modules/update/update.fetch.inc modules/update/update.fetch.inc
index 41beef1b..9c98601 100644
--- modules/update/update.fetch.inc
+++ modules/update/update.fetch.inc
@@ -254,7 +254,9 @@ class update_xml_parser {
         $this->current_object = &$this->current_release;
         break;
       default:
-        $this->current_object[strtolower($this->current_tag)] = trim($this->current_object[strtolower($this->current_tag)]);
+        if (isset($this->current_object[strtolower($this->current_tag)])) {
+          $this->current_object[strtolower($this->current_tag)] = trim($this->current_object[strtolower($this->current_tag)]);
+        }
         $this->current_tag = '';
     }
   }