Index: modules/node/node.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.module,v
retrieving revision 1.898
diff -u -p -r1.898 node.module
--- modules/node/node.module	5 Nov 2007 15:14:54 -0000	1.898
+++ modules/node/node.module	11 Nov 2007 22:39:28 -0000
@@ -912,9 +912,10 @@ function node_prepare($node, $teaser = F
   // First we'll overwrite the existing node teaser and body with
   // the filtered copies! Then, we'll stick those into the content
   // array and set the read more flag if appropriate.
-  $node->readmore = (strlen($node->teaser) < strlen($node->body));
+  $node->readmore = $teaser && ($node->teaser !== '') && (trim($node->teaser) !== trim($node->body));
 
   if ($teaser == FALSE) {
+
     $node->body = check_markup($node->body, $node->format, FALSE);
   }
   else {