diff --git a/blocks/comments/lib.php b/blocks/comments/lib.php
index 4e2d828d39ad0..3f10939bb3dc8 100644
--- a/blocks/comments/lib.php
+++ b/blocks/comments/lib.php
@@ -37,7 +37,7 @@
  * }
  * @return boolean
  */
-function comments_comment_validate($comment_param) {
+function block_comments_comment_validate($comment_param) {
     if ($comment_param->commentarea != 'page_comments') {
         throw new comment_exception('invalidcommentarea');
     }
@@ -53,7 +53,7 @@ function comments_comment_validate($comment_param) {
  * @param stdClass $args
  * @return array
  */
-function comments_comment_permissions($args) {
+function block_comments_comment_permissions($args) {
     return array('post'=>true, 'view'=>true);
 }
 
@@ -64,7 +64,7 @@ function comments_comment_permissions($args) {
  * @param stdClass $args
  * @return boolean
  */
-function comments_comment_display($comments, $args) {
+function block_comments_comment_display($comments, $args) {
     if ($args->commentarea != 'page_comments') {
         throw new comment_exception('invalidcommentarea');
     }
diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index e2cde0b755d4e..da0ce385b98f3 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -7552,12 +7552,20 @@ function get_list_of_plugins($directory='mod', $exclude='', $basedir='') {
  * @return mixed
  */
 function plugin_callback($type, $name, $feature, $action, $options = null, $default=null) {
+    global $CFG;
+
     $component = clean_param($type . '_' . $name, PARAM_COMPONENT);
     if (empty($component)) {
         throw coding_exception('Invalid component used in plugin_callback():' . $type . '_' . $name);
     }
 
-    $function = $name.'_'.$feature.'_'.$action;
+    list($type, $name) = normalize_component($component);
+    $component = $type . '_' . $name;
+
+    $function = null;
+
+    $function = $component.'_'.$feature.'_'.$action;
+    $oldfunction = $name.'_'.$feature.'_'.$action;
 
     $dir = get_component_directory($component);
     if (empty($dir)) {
@@ -7569,6 +7577,13 @@ function plugin_callback($type, $name, $feature, $action, $options = null, $defa
         require_once($dir.'/lib.php');
     }
 
+    if (!function_exists($function) and function_exists($oldfunction)) {
+        if ($type !== 'mod' and $type !== 'core') {
+            debugging("Please use new function name $function instead of legacy $oldfunction");
+        }
+        $function = $oldfunction;
+    }
+
     if (function_exists($function)) {
         // Function exists, so just return function result
         $ret = call_user_func_array($function, (array)$options);