diff --git a/includes/handlers.inc b/includes/handlers.inc
index 091e625..02a31c8 100644
--- a/includes/handlers.inc
+++ b/includes/handlers.inc
@@ -406,6 +406,10 @@ function set_relationship() {
    * Add this handler into the query.
    *
    * If we were using PHP5, this would be abstract.
+   *
+   * @param bool $group_by
+   *   (optional) Whether the view is using an aggregation query. If you
+   *    override this method you can specify $group_by as optional parameter.
    */
   function query() { }
 
diff --git a/modules/comment/views_plugin_row_comment_view.inc b/modules/comment/views_plugin_row_comment_view.inc
index f3f58dc..8a21405 100644
--- a/modules/comment/views_plugin_row_comment_view.inc
+++ b/modules/comment/views_plugin_row_comment_view.inc
@@ -22,7 +22,7 @@ function options_form(&$form, &$form_state) {
     );
   }
 
-  function pre_render($result) {
+  function pre_render(&$result) {
     $cids = array();
     $this->comments = array();
 
diff --git a/plugins/views_plugin_display_attachment.inc b/plugins/views_plugin_display_attachment.inc
index e59ba62..3096944 100644
--- a/plugins/views_plugin_display_attachment.inc
+++ b/plugins/views_plugin_display_attachment.inc
@@ -14,7 +14,7 @@
  * @ingroup views_display_plugins
  */
 class views_plugin_display_attachment extends views_plugin_display {
-  function option_definition () {
+  function option_definition() {
     $options = parent::option_definition();
 
     $options['attachment_position'] = array('default' => 'before');
diff --git a/plugins/views_plugin_row.inc b/plugins/views_plugin_row.inc
index 2fe3ae4..9af9daf 100644
--- a/plugins/views_plugin_row.inc
+++ b/plugins/views_plugin_row.inc
@@ -122,7 +122,7 @@ function query() {
    * @param $result
    *   The full array of results from the query.
    */
-  function pre_render($result) { }
+  function pre_render(&$result) { }
 
   /**
    * Render a row object. This usually passes through to a theme template
diff --git a/plugins/views_plugin_style.inc b/plugins/views_plugin_style.inc
index 39c4abb..4c1fc54 100644
--- a/plugins/views_plugin_style.inc
+++ b/plugins/views_plugin_style.inc
@@ -122,7 +122,7 @@ function build_sort_post() { }
    * @param $result
    *   The full array of results from the query.
    */
-  function pre_render($result) {
+  function pre_render(&$result) {
     if (!empty($this->row_plugin)) {
       $this->row_plugin->pre_render($result);
     }