Index: phptemplate.engine
===================================================================
RCS file: /cvs/drupal/drupal/themes/engines/phptemplate/phptemplate.engine,v
retrieving revision 1.23
diff -u -p -r1.23 phptemplate.engine
--- phptemplate.engine	31 Dec 2005 10:48:56 -0000	1.23
+++ phptemplate.engine	6 Jan 2006 08:07:23 -0000
@@ -57,7 +57,11 @@ function _phptemplate_callback($hook, $v
 
   // Allow specified variables to be overridden
   if (function_exists('_phptemplate_variables')) {
-    $variables = array_merge($variables, _phptemplate_variables($hook, $variables));
+    $ret = _phptemplate_variables($hook, $variables);
+    if(is_array($ret))
+	{
+    $variables = array_merge($variables, $ret);
+	}
   }
 
   if (isset($variables['template_file'])) {