diff --git a/core/lib/Drupal/Core/Entity/EntityFormController.php b/core/lib/Drupal/Core/Entity/EntityFormController.php
index 067fe17..6982a26 100644
--- a/core/lib/Drupal/Core/Entity/EntityFormController.php
+++ b/core/lib/Drupal/Core/Entity/EntityFormController.php
@@ -46,6 +46,7 @@ public function __construct($operation = NULL) {
    *   The name of the current operation.
    */
   public function setOperation($operation) {
+    // If NULL is passed, do not overwrite the operation.
     if ($operation) {
       $this->operation = $operation;
     }
diff --git a/core/lib/Drupal/Core/Entity/HtmlEntityFormController.php b/core/lib/Drupal/Core/Entity/HtmlEntityFormController.php
index 8237ba1..79ef787 100644
--- a/core/lib/Drupal/Core/Entity/HtmlEntityFormController.php
+++ b/core/lib/Drupal/Core/Entity/HtmlEntityFormController.php
@@ -16,7 +16,7 @@
 class HtmlEntityFormController extends HtmlFormController {
 
   /**
-   * {@inheritdoc}
+   * Overrides \Drupal\Core\HtmlFormController::content().
    *
    * Due to reflection, the argument must be named $_entity_form. The parent
    * method has $request and $_form, but the parameter must match the route.
@@ -28,8 +28,8 @@ public function content(Request $request, $_entity_form) {
   /**
    * Overrides \Drupal\Core\HtmlFormController::getFormObject().
    *
-   * Instead of a class name or service ID, $form_arg will be a string representing
-   * the entity and operation being performed.
+   * Instead of a class name or service ID, $form_arg will be a string
+   * representing the entity and operation being performed.
    * Consider the following route:
    * @code
    *   pattern: '/foo/{node}/bar'
@@ -50,16 +50,16 @@ protected function getFormObject(Request $request, $form_arg) {
 
     // If no operation is provided, use 'default'.
     $form_arg .= '.default';
-    list ($entity, $operation) = explode('.', $form_arg);
+    list ($entity_type, $operation) = explode('.', $form_arg);
 
-    if ($request->attributes->has($entity)) {
-      $entity = $request->attributes->get($entity);
+    if ($request->attributes->has($entity_type)) {
+      $entity = $request->attributes->get($entity_type);
     }
     else {
-      $entity = $manager->getStorageController($entity)->create(array());
+      $entity = $manager->getStorageController($entity_type)->create(array());
     }
 
-    return $manager->getFormController($entity->entityType(), $operation)->setEntity($entity);
+    return $manager->getFormController($entity_type, $operation)->setEntity($entity);
   }
 
 }