diff --git a/index.php b/index.php
index e289cdc..a6393a7 100644
--- a/index.php
+++ b/index.php
@@ -1,5 +1,7 @@
 <?php
 
+define('INCLUDES_ALLOWED');
+
 require("static/web.php");
 require("lib/request.php");
 
diff --git a/lib/base.php b/lib/base.php
index 2c944cc..5e8b401 100644
--- a/lib/base.php
+++ b/lib/base.php
@@ -7,6 +7,10 @@
  * desc: Basisklasse für die Klassen Request und Registrator.
  */
 
+
+if (!defined('INCLUDES_ALLOWED'))
+    die('Access denied.');
+
 require("db.php");
 require("config.php");
 require("logger.php");
diff --git a/lib/config.php b/lib/config.php
index e0112ee..1c4f8bd 100644
--- a/lib/config.php
+++ b/lib/config.php
@@ -1,6 +1,9 @@
 <?php
 
 
+if (!defined('INCLUDES_ALLOWED'))
+    die('Access denied.');
+
 class Config {
 
     private $config = [];
diff --git a/lib/db.php b/lib/db.php
index d7359f1..acd5e41 100644
--- a/lib/db.php
+++ b/lib/db.php
@@ -8,6 +8,9 @@
  */
 
 
+if (!defined('INCLUDES_ALLOWED'))
+    die('Access denied.');
+
 function testDriver(): bool
 {
     print_r(PDO::getAvailableDrivers());
diff --git a/lib/logger.php b/lib/logger.php
index 174b962..1df634c 100644
--- a/lib/logger.php
+++ b/lib/logger.php
@@ -8,6 +8,9 @@
  */
 
 
+if (!defined('INCLUDES_ALLOWED'))
+    die('Access denied.');
+
 class Logger {
 
     /**
diff --git a/lib/register.php b/lib/register.php
index db7e17f..9c04ee7 100644
--- a/lib/register.php
+++ b/lib/register.php
@@ -8,6 +8,10 @@
  * User am synapse-matrix Server. Achtung: z.Z. noch keine Registrierung!
  */
 
+
+if (!defined('INCLUDES_ALLOWED'))
+    die('Access denied.');
+
 require("base.php");
 
 
diff --git a/lib/request.php b/lib/request.php
index 49eb039..2d22241 100644
--- a/lib/request.php
+++ b/lib/request.php
@@ -7,6 +7,10 @@
  * desc:
  */
 
+
+if (!defined('INCLUDES_ALLOWED'))
+    die('Access denied.');
+
 require("base.php");
 require("static/mail.php");
 
diff --git a/static/mail.php b/static/mail.php
index be4cd7c..d1c130d 100644
--- a/static/mail.php
+++ b/static/mail.php
@@ -8,6 +8,9 @@
  */
 
 
+if (!defined('INCLUDES_ALLOWED'))
+    die('Access denied.');
+
 const MAILTEXT1 = <<<END
 Wir freuen uns, daß Sie sich für einen Account bei
 END;
diff --git a/static/web.php b/static/web.php
index 0829198..bf0275e 100644
--- a/static/web.php
+++ b/static/web.php
@@ -8,6 +8,9 @@
  */
 
 
+if (!defined('INCLUDES_ALLOWED'))
+    die('Access denied.');
+
 // HTML
 const HTML_META = <<<END
 <meta charset="utf-8" />
diff --git a/validation.php b/validation.php
index 80b624e..65f6551 100644
--- a/validation.php
+++ b/validation.php
@@ -1,5 +1,7 @@
 <?php
 
+define('INCLUDES_ALLOWED');
+
 require("static/web.php");
 require("lib/register.php");