diff --git a/core/modules/filter/lib/Drupal/filter/Tests/FilterFormatAccessTest.php b/core/modules/filter/lib/Drupal/filter/Tests/FilterFormatAccessTest.php
index 6daa1d4..f2aae1b 100644
--- a/core/modules/filter/lib/Drupal/filter/Tests/FilterFormatAccessTest.php
+++ b/core/modules/filter/lib/Drupal/filter/Tests/FilterFormatAccessTest.php
@@ -225,7 +225,7 @@ function testFormatWidgetPermissions() {
     $this->assertText($edit[$body_value_key], 'Old body found in preview.');
 
     // Save and verify that only the title was changed.
-    $this->drupalPost('node/' . $node->nid . '/edit', $new_edit, t('Preview'), array('query' => array('tempstore_id' => $node->uuid)));
+    $this->drupalPost('node/' . $node->nid . '/edit', $new_edit, t('Save'));
     $this->assertNoText($edit['title'], 'Old title not found.');
     $this->assertText($new_edit['title'], 'New title found.');
     $this->assertText($edit[$body_value_key], 'Old body found.');
diff --git a/core/modules/node/lib/Drupal/node/Tests/PagePreviewTest.php b/core/modules/node/lib/Drupal/node/Tests/PagePreviewTest.php
index 77575c1..532e1e3 100644
--- a/core/modules/node/lib/Drupal/node/Tests/PagePreviewTest.php
+++ b/core/modules/node/lib/Drupal/node/Tests/PagePreviewTest.php
@@ -45,10 +45,11 @@ function testPagePreview() {
     $this->assertText($edit[$title_key], 'Title displayed.');
     $this->assertText($edit[$body_key], 'Body displayed.');
 
-    // Check that the title and body fields are displayed with the correct values
-    // after going back to the content edit page.
+    // Check that the title and body fields are displayed with the correct
+    // values after going back to the content edit page.
     $url = parse_url($this->getUrl());
-    list(, , , $tempstore_id) = explode('/', $url['path']);
+    $paths = explode('/', $url['path']);
+    $tempstore_id = array_pop($paths);
     $options = array('query' => array('tempstore_id' => $tempstore_id));
     $this->drupalGet('node/add/page', $options);
     $this->assertFieldByName($title_key, $edit[$title_key], 'Title field displayed.');
@@ -77,10 +78,11 @@ function testPagePreviewWithRevisions() {
     $this->assertText($edit[$title_key], 'Title displayed.');
     $this->assertText($edit[$body_key], 'Body displayed.');
 
-    // Check that the title and body fields are displayed with the correct values
-    // after going back to the content edit page.
+    // Check that the title and body fields are displayed with the correct
+    // values after going back to the content edit page.
     $url = parse_url($this->getUrl());
-    list(, , , $tempstore_id) = explode('/', $url['path']);
+    $paths = explode('/', $url['path']);
+    $tempstore_id = array_pop($paths);
     $options = array('query' => array('tempstore_id' => $tempstore_id));
     $this->drupalGet('node/add/page', $options);
     $this->assertFieldByName($title_key, $edit[$title_key], 'Title field displayed.');
diff --git a/core/modules/node/node.module b/core/modules/node/node.module
index a957c81..4792e19 100644
--- a/core/modules/node/node.module
+++ b/core/modules/node/node.module
@@ -1753,11 +1753,11 @@ function node_menu() {
     'type' => MENU_DEFAULT_LOCAL_TASK,
     'weight' => -10,
   );
-  // @todo real access check.
   $items['node/preview/%node_tempstore'] = array(
     'page callback' => 'node_preview',
     'page arguments' => array(2),
-    'access callback' => TRUE,
+    'access callback' => 'node_access_preview',
+    'access arguments' => array(2),
     'file' => 'node.pages.inc',
   );
   $items['node/%node/edit'] = array(
@@ -2299,13 +2299,13 @@ function node_page_build(&$page) {
 /**
  * Get the preview form selection box.
  *
- * @param string $bundle
- *   The name of the node bundle.
+ * @param Drupal\node\Node $node
+ *   A node entity.
  *
  * @return $form
  *   The view mode preview selection form.
  */
-function node_preview_form_select($form, $form_state, $node) {
+function node_preview_form_select($form, $form_state, Node $node) {
 
   // Always add default.
   $view_mode_options = array('default' => t('Full'));
@@ -2808,6 +2808,24 @@ function node_node_access($node, $op, $account) {
 }
 
 /**
+ * Access callback: Checks a user's permission for previewing a node.
+ *
+ * @param Drupal\node\Node|string|stdClass $node
+ *   The node entity to be previewed.
+ *
+ * @return
+ *   TRUE if the user has access to the preview, FALSE otherwise.
+ *
+ * @see node_menu()
+ */
+function node_access_preview($node) {
+  if (node_access('create', $node) || node_access('update', $node)) {
+    return TRUE;
+  }
+  return;
+}
+
+/**
  * Helper function to generate standard node permission list for a given type.
  *
  * @param $name
diff --git a/core/modules/node/node.pages.inc b/core/modules/node/node.pages.inc
index 490f09c..639e264 100644
--- a/core/modules/node/node.pages.inc
+++ b/core/modules/node/node.pages.inc
@@ -119,54 +119,50 @@ function node_add($node_type) {
  * @param Drupal\node\Node $node
  *   The node to preview.
  *
- * @return
- *   An HTML-formatted string of a node preview.
+ * @return array
+ *   A form array as expected by drupal_render().
  */
 function node_preview(Node $node) {
 
-  // @todo move access check earlier ?
-  if (node_access('create', $node) || node_access('update', $node)) {
-
-    // Set status to true so we don't get the 'unpublished' css.
-    $node->status = TRUE;
+  // Set status to true so we don't get the 'unpublished' css.
+  $node->status = TRUE;
 
-    _field_invoke_multiple('load', 'node', array($node->nid => $node));
-    // Load the user's name when needed.
-    if (isset($node->name)) {
-      // The use of isset() is mandatory in the context of user IDs, because
-      // user ID 0 denotes the anonymous user.
-      if ($user = user_load_by_name($node->name)) {
-        $node->uid = $user->uid;
-      }
-      else {
-        $node->uid = 0; // anonymous user
-      }
+  _field_invoke_multiple('load', 'node', array($node->nid => $node));
+  // Load the user's name when needed.
+  if (isset($node->name)) {
+    // The use of isset() is mandatory in the context of user IDs, because
+    // user ID 0 denotes the anonymous user.
+    if ($user = user_load_by_name($node->name)) {
+      $node->uid = $user->uid;
     }
-    elseif ($node->uid) {
-      $user = user_load($node->uid);
-      $node->name = $user->name;
+    else {
+      $node->uid = 0; // anonymous user
     }
+  }
+  elseif ($node->uid) {
+    $user = user_load($node->uid);
+    $node->name = $user->name;
+  }
 
-    $node->changed = REQUEST_TIME;
-
-    // Get the view mode to render the preview in.
-    $view_mode = drupal_container()->get('request')->query->get('view_mode');
-    if (empty($view_mode)) {
-      $view_mode = 'full';
-    }
+  $node->changed = REQUEST_TIME;
 
-    // Property so we can manipulate $page in template_preprocess_node.
-    if ($view_mode == 'full' || $view_mode == 'default') {
-      drupal_set_title($node->title);
-      $node->node_page_title = TRUE;
-    }
+  // Get the view mode to render the preview in.
+  $view_mode = drupal_container()->get('request')->query->get('view_mode');
+  if (empty($view_mode)) {
+    $view_mode = 'full';
+  }
 
-    $build = array();
-    // @todo all links should be disabled, except for returning to the edit form.
-    $build['#attached']['library'][] = array('node', 'drupal.node.preview');
-    $build['preview'] = node_view($node, $view_mode);
-    return $build;
+  // Property so we can manipulate $page in template_preprocess_node.
+  if ($view_mode == 'full' || $view_mode == 'default') {
+    drupal_set_title($node->title);
+    $node->node_page_title = TRUE;
   }
+
+  $build = array();
+  // @todo all links should be disabled, except for returning to the edit form.
+  $build['#attached']['library'][] = array('node', 'drupal.node.preview');
+  $build['preview'] = node_view($node, $view_mode);
+  return $build;
 }
 
 /**
diff --git a/core/modules/poll/lib/Drupal/poll/Tests/PollTestBase.php b/core/modules/poll/lib/Drupal/poll/Tests/PollTestBase.php
index bfb5387..7721007 100644
--- a/core/modules/poll/lib/Drupal/poll/Tests/PollTestBase.php
+++ b/core/modules/poll/lib/Drupal/poll/Tests/PollTestBase.php
@@ -74,7 +74,8 @@ function pollCreate($title, $choices, $preview = TRUE) {
     if ($preview) {
       $this->drupalPost(NULL, $edit, t('Preview'));
       $url = parse_url($this->getUrl());
-      list(, , , $tempstore_id) = explode('/', $url['path']);
+      $paths = explode('/', $url['path']);
+      $tempstore_id = array_pop($paths);
       $post_url = 'node/add/poll';
       $options = array('query' => array('tempstore_id' => $tempstore_id));
       $this->drupalGet('node/add/poll', $options);