--- modules/node/node.module.orig   2008-06-16 15:53:55.000000000 -0400
+++ modules/node/node.module        2008-06-16 15:53:59.000000000 -0400
@@ -1988,7 +1988,7 @@ function node_validate($node, $form = ar
     }
 
     // Validate the "authored on" field. As of PHP 5.1.0, strtotime returns FALSE instead of -1 upon failure.
-    if (!empty($node->date) && strtotime($node->date) <= 0) {
+    if (!empty($node->date) && (strtotime($node->date) == -1 || strtotime($node->date) === false)) {
       form_set_error('date', t('You have to specify a valid date.'));
     }
   }