diff --git a/openpub-base.php b/openpub-base.php
index c042be2..6ac6054 100644
--- a/openpub-base.php
+++ b/openpub-base.php
@@ -20,21 +20,20 @@
     die;
 }
 
-/**
- * Manual loaded file: the autoloader.
- */
-require_once __DIR__ . '/autoloader.php';
-$autoloader = new OWC\OpenPub\Base\Autoloader();
-
 /**
  * Not all the members of the OpenWebconcept are using composer in the root of their project.
  * Therefore they are required to run a composer install inside this plugin directory.
  * In this case the composer autoload file needs to be required.
+ *
+ * If this plugin is not installed with composer a custom autoloader is used.
  */
-$composerAutoload = __DIR__ . '/vendor/autoload.php';
-
-if (file_exists($composerAutoload)) {
-    require_once $composerAutoload;
+if (!class_exists(\OWC\OpenPub\Base\Foundation\Plugin::class)) {
+    if (file_exists(__DIR__ . '/vendor/autoload.php')) {
+        require_once __DIR__ . '/vendor/autoload.php';
+    } else {
+        require_once __DIR__ . '/autoloader.php';
+        $autoloader = new \OWC\OpenPub\Base\Autoloader();
+    }
 }
 
 /**
@@ -45,9 +44,8 @@
  * and wp_loaded action hooks.
  */
 add_action('plugins_loaded', function () {
-    $plugin = (new OWC\OpenPub\Base\Foundation\Plugin(__DIR__));
-
-    add_action('after_setup_theme', function () use ($plugin) {
+    add_action('after_setup_theme', function () {
+        $plugin = (new OWC\OpenPub\Base\Foundation\Plugin(__DIR__));
         $plugin->boot();
         do_action('owc/openpub-base/plugin', $plugin);
     });