--- old_apachesolr.module	Mon Jan 26 13:17:31 2009
+++ apachesolr.module	Mon Jan 26 13:17:49 2009
@@ -538,7 +538,7 @@ function apachesolr_node_to_document($ni
  * http://lucene.apache.org/solr/api/org/apache/solr/schema/DateField.html
  */
 function apachesolr_date_iso($date_timestamp) {
-  return date('Y-m-d\TH:i:s\Z', $date_timestamp);
+  return gmdate('Y-m-d\TH:i:s\Z', $date_timestamp);
 }
 
 /**