diff --git a/date.field.inc b/date.field.inc
index fa81180..26e87b9 100644
--- a/date.field.inc
+++ b/date.field.inc
@@ -339,7 +339,7 @@ function date_field_validate($entity_type, $entity, $field, $instance, $langcode
   // since the element won't have been munged back into a date.
   if (!form_get_errors()) {
     foreach ($items as $delta => $item) {
-      if (is_array($item) && isset($item['value'])) {
+      if (is_array($item) && isset($item['value']) && isset($item['timezone'])) {
         $process = date_process_values($field, $instance);
         $date1 = new DateObject($item['value'], $item['timezone'], date_type_format($field['type']));
         if (count($process) == 1 || (empty($item['value2']) && $item['value2'] !== 0)) {