diff --git a/mod/lesson/db/access.php b/mod/lesson/db/access.php
index e7e6a12f642..bb8028bf120 100644
--- a/mod/lesson/db/access.php
+++ b/mod/lesson/db/access.php
@@ -25,6 +25,8 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or late
  */
 
+defined('MOODLE_INTERNAL') || die();
+
 $capabilities = array(
 
     'mod/lesson:edit' => array(
diff --git a/mod/lesson/db/install.php b/mod/lesson/db/install.php
index 5501b7650c4..b94af322d70 100644
--- a/mod/lesson/db/install.php
+++ b/mod/lesson/db/install.php
@@ -26,6 +26,8 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 o
  */
 
+defined('MOODLE_INTERNAL') || die();
+
 function xmldb_lesson_install() {
     global $DB;
 
diff --git a/mod/lesson/db/upgrade.php b/mod/lesson/db/upgrade.php
index f172b04274f..aae2ace78bf 100644
--- a/mod/lesson/db/upgrade.php
+++ b/mod/lesson/db/upgrade.php
@@ -41,6 +41,8 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 o
  */
 
+defined('MOODLE_INTERNAL') || die();
+
 function xmldb_lesson_upgrade($oldversion) {
     global $CFG, $DB, $OUTPUT;