diff --git a/core/lib/Drupal/Component/Plugin/Discovery/AnnotatedClassDiscovery.php b/core/lib/Drupal/Component/Plugin/Discovery/AnnotatedClassDiscovery.php
index 715bbfe..377bf4a 100644
--- a/core/lib/Drupal/Component/Plugin/Discovery/AnnotatedClassDiscovery.php
+++ b/core/lib/Drupal/Component/Plugin/Discovery/AnnotatedClassDiscovery.php
@@ -84,8 +84,6 @@ public function getDefinitions() {
 
     // Search for classes within all PSR-0 namespace locations.
     foreach ($this->getPluginNamespaces() as $namespace => $dirs) {
-      // Extract the module name from this namespace.
-      $module = $this->getModuleFromNamespace($namespace);
       foreach ($dirs as $dir) {
         $dir .= DIRECTORY_SEPARATOR . str_replace('\\', DIRECTORY_SEPARATOR, $namespace);
         if (file_exists($dir)) {
@@ -105,7 +103,6 @@ public function getDefinitions() {
                 // instead of requiring us to work with the annotation object.
                 $definition = $annotation->get();
                 $definition['class'] = $class;
-                $definition['module'] = $module;
                 $definitions[$definition['id']] = $definition;
               }
             }
@@ -117,25 +114,6 @@ public function getDefinitions() {
   }
 
   /**
-   * Extracts a module name from a Drupal namespace.
-   *
-   * @param string $namespace
-   *   The namespace to extract the module name from.
-   *
-   * @return string|null
-   *   The matches module name, or NULL otherwise.
-   */
-  protected function getModuleFromNamespace($namespace) {
-    preg_match('|^Drupal\\\\(?<module>[\w]+)\\\\|', $namespace, $matches);
-
-    if (isset($matches['module'])) {
-      return $matches['module'];
-    }
-
-    return NULL;
-  }
-
-  /**
    * Returns an array of PSR-0 namespaces to search for plugin classes.
    */
   protected function getPluginNamespaces() {
diff --git a/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php b/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
index 8a45afc..2d19517 100644
--- a/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/AnnotatedClassDiscovery.php
@@ -65,6 +65,38 @@ function __construct($subdir, \Traversable $root_namespaces, $annotation_namespa
   /**
    * {@inheritdoc}
    */
+  public function getDefinitions() {
+    $definitions = parent::getDefinitions();
+    foreach ($definitions as &$definition) {
+      // Extract the module name from the class namespace.
+      $definition['module'] = $this->getModuleFromNamespace($definition['class']);
+    }
+    return $definitions;
+  }
+
+  /**
+   * Extracts a module name from a Drupal namespace.
+   *
+   * @param string $namespace
+   *   The namespace to extract the module name from.
+   *
+   * @return string|null
+   *   The matches module name, or NULL otherwise.
+   */
+  protected function getModuleFromNamespace($namespace) {
+    preg_match('|^Drupal\\\\(?<module>[\w]+)\\\\|', $namespace, $matches);
+
+    if (isset($matches['module'])) {
+      return $matches['module'];
+    }
+
+    return NULL;
+  }
+
+
+  /**
+   * {@inheritdoc}
+   */
   protected function getPluginNamespaces() {
     $plugin_namespaces = array();
     foreach ($this->rootNamespacesIterator as $namespace => $dir) {