diff --git a/modules/backend/ServiceProvider.php b/modules/backend/ServiceProvider.php
index 5933c03797..1dedc46b87 100644
--- a/modules/backend/ServiceProvider.php
+++ b/modules/backend/ServiceProvider.php
@@ -19,6 +19,8 @@ class ServiceProvider extends ModuleServiceProvider
      */
     public function register()
     {
+        parent::register();
+
         $this->registerConsole();
         $this->registerMailer();
         $this->registerAssetBundles();
diff --git a/modules/cms/ServiceProvider.php b/modules/cms/ServiceProvider.php
index a394973966..609528428a 100644
--- a/modules/cms/ServiceProvider.php
+++ b/modules/cms/ServiceProvider.php
@@ -34,6 +34,8 @@ class ServiceProvider extends ModuleServiceProvider
      */
     public function register()
     {
+        parent::register();
+
         $this->registerConsole();
         $this->registerTwigParser();
         $this->registerAssetBundles();
diff --git a/modules/system/ServiceProvider.php b/modules/system/ServiceProvider.php
index ec4e8b11bc..90ca44ae2e 100644
--- a/modules/system/ServiceProvider.php
+++ b/modules/system/ServiceProvider.php
@@ -35,6 +35,8 @@ class ServiceProvider extends ModuleServiceProvider
      */
     public function register()
     {
+        parent::register();
+
         $this->registerSingletons();
         $this->registerPrivilegedActions();
 
diff --git a/modules/system/classes/PluginManager.php b/modules/system/classes/PluginManager.php
index d29d28a839..cd39f86472 100644
--- a/modules/system/classes/PluginManager.php
+++ b/modules/system/classes/PluginManager.php
@@ -150,6 +150,8 @@ public function loadPlugin(string $namespace, string $path): ?PluginBase
         $className = $namespace . '\Plugin';
         $classPath = $path . '/Plugin.php';
 
+        $this->app->make(ClassLoader::class)->autoloadPackage($namespace, $path);
+
         try {
             // Autoloader failed?
             if (!class_exists($className)) {
diff --git a/modules/system/tests/bootstrap/app.php b/modules/system/tests/bootstrap/app.php
index 9be7e9d5db..11dd502e78 100644
--- a/modules/system/tests/bootstrap/app.php
+++ b/modules/system/tests/bootstrap/app.php
@@ -17,7 +17,34 @@
 );
 
 $loader->register();
-$loader->addDirectories([
-    'modules',
-    'plugins'
-]);
+
+/*
+ * Manually register all module classes for autoloading
+ */
+foreach (glob($baseDir . '/modules/*', GLOB_ONLYDIR) as $modulePath) {
+    $loader->autoloadPackage(basename($modulePath), $modulePath);
+}
+
+/*
+ * Manually register all plugin classes for autoloading
+ */
+$dirPath = $baseDir . '/plugins';
+if (is_dir($dirPath)) {
+    $it = new RecursiveIteratorIterator(
+        new RecursiveDirectoryIterator($dirPath, FilesystemIterator::FOLLOW_SYMLINKS)
+    );
+    $it->setMaxDepth(2);
+    $it->rewind();
+
+    while ($it->valid()) {
+        if (($it->getDepth() > 1) && $it->isFile() && (strtolower($it->getFilename()) === "plugin.php")) {
+            $filePath = dirname($it->getPathname());
+            $pluginName = basename($filePath);
+            $vendorName = basename(dirname($filePath));
+
+            $loader->autoloadPackage($vendorName . '\\' . $pluginName, $filePath);
+        }
+
+        $it->next();
+    }
+}