diff --git a/readme.txt b/readme.txt
index 7c5ef1b..944f68c 100644
--- a/readme.txt
+++ b/readme.txt
@@ -79,6 +79,7 @@ Is this plugin prepared for multisites? Yes.
 * Added DataTables language support for 'search'.
 * Added VSCode settings.json for formatOnSave.
 * Added .gitignore.
+* Added security measurement to prevent the public to run the php-script directly.
 
 = 4.1.0 =
 * Compatibility with WordPress version 6.7.1
diff --git a/wp-jquery-datatable.php b/wp-jquery-datatable.php
index f465859..9db1812 100644
--- a/wp-jquery-datatable.php
+++ b/wp-jquery-datatable.php
@@ -9,6 +9,10 @@
  * WordPress Tested up to: 7.0.2
  */
 
+if (!defined('ABSPATH')) {
+    die('Invalid request.');
+}
+
 register_activation_hook(__FILE__, 'wp_jdt_activate_plugin');
 function wp_jdt_activate_plugin()
 {