diff --git a/mod/lesson/backuplib.php b/mod/lesson/backuplib.php
index b9fc75c3650..231aa961fd7 100644
--- a/mod/lesson/backuplib.php
+++ b/mod/lesson/backuplib.php
@@ -54,6 +54,8 @@
 //
 //-----------------------------------------------------------
 
+defined('MOODLE_INTERNAL') || die();
+
 /**
  * This function executes all the backup procedure about this mod
  */
diff --git a/mod/lesson/import_form.php b/mod/lesson/import_form.php
index 201185ef2fb..1fa5d33a373 100644
--- a/mod/lesson/import_form.php
+++ b/mod/lesson/import_form.php
@@ -23,6 +23,8 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  **/
 
+defined('MOODLE_INTERNAL') || die();
+
 /**
  * Form used to select a file and file format for the import
  * @copyright 2009 Sam Hemelryk
diff --git a/mod/lesson/importpptlib.php b/mod/lesson/importpptlib.php
index 2161dae69ad..b6d2a5c82b7 100644
--- a/mod/lesson/importpptlib.php
+++ b/mod/lesson/importpptlib.php
@@ -24,6 +24,8 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  **/
 
+defined('MOODLE_INTERNAL') || die();
+
 /**
  * A recursive function to build a html list
  *
diff --git a/mod/lesson/lib.php b/mod/lesson/lib.php
index c2f08ce91a0..562c0f980b6 100644
--- a/mod/lesson/lib.php
+++ b/mod/lesson/lib.php
@@ -23,6 +23,8 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  **/
 
+defined('MOODLE_INTERNAL') || die();
+
 /* Do not include any libraries here! */
 
 /**
diff --git a/mod/lesson/reformat.php b/mod/lesson/reformat.php
index 4f4ec0ace5b..b6fa6b5bef3 100644
--- a/mod/lesson/reformat.php
+++ b/mod/lesson/reformat.php
@@ -23,6 +23,8 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or late
  **/
 
+defined('MOODLE_INTERNAL') || die();
+
 function removedoublecr($filename) {
 // This function will adjust a file in roughly Aiken style by replacing extra newlines with <br/> tags
 // so that instructors can have newlines wherever they like as long as the overall format is in Aiken
diff --git a/mod/lesson/restorelib.php b/mod/lesson/restorelib.php
index 4ae9cef2aaf..c4573cbba1e 100644
--- a/mod/lesson/restorelib.php
+++ b/mod/lesson/restorelib.php
@@ -54,6 +54,8 @@
     //
     //-----------------------------------------------------------
 
+defined('MOODLE_INTERNAL') || die();
+
     //This function executes all the restore procedure about this mod
     function lesson_restore_mods($mod,$restore) {
         global $CFG, $DB;