Index: includes/theme.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/theme.inc,v
retrieving revision 1.613
diff -u -p -r1.613 theme.inc
--- includes/theme.inc	24 Sep 2010 00:37:41 -0000	1.613
+++ includes/theme.inc	24 Sep 2010 15:36:22 -0000
@@ -870,6 +870,7 @@ function theme($hook, $variables = array
   }
 
   // Generate the output using either a function or a template.
+  $output = '';
   if (isset($info['function'])) {
     if (function_exists($info['function'])) {
       $output = $info['function']($variables);