diff --git a/core/modules/filter/src/Entity/FilterFormat.php b/core/modules/filter/src/Entity/FilterFormat.php
index 94a5bb3..8bda458 100644
--- a/core/modules/filter/src/Entity/FilterFormat.php
+++ b/core/modules/filter/src/Entity/FilterFormat.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\filter\Entity;
 
+use Drupal\Component\Utility\DiffArray;
 use Drupal\Core\Config\Entity\ConfigEntityBase;
 use Drupal\Core\Entity\EntityWithPluginBagsInterface;
 use Drupal\Core\Entity\EntityStorageInterface;
@@ -200,7 +201,7 @@ public function preSave(EntityStorageInterface $storage) {
       if (!$filter['status']) {
         // Compare the current settings to the default settings. If there are
         // any customisations save them to configuration.
-        $diff = array_diff($filter, $default);
+        $diff = DiffArray::diffAssocRecursive($filter, $default);
         return !empty($diff);
       }
       return TRUE;
diff --git a/core/modules/filter/src/Tests/FilterAPITest.php b/core/modules/filter/src/Tests/FilterAPITest.php
index 2c5522a..383a7c0 100644
--- a/core/modules/filter/src/Tests/FilterAPITest.php
+++ b/core/modules/filter/src/Tests/FilterAPITest.php
@@ -335,6 +335,50 @@ function testTypedDataAPI() {
   }
 
   /**
+   * Tests that FilterFormat::preSave() only saves customised plugins.
+   */
+  public function testFilterFormatPreSave() {
+    /** @var \Drupal\filter\FilterFormatInterface $crazy_format */
+    $crazy_format = entity_create('filter_format', array(
+      'format' => 'crazy',
+      'name' => 'Crazy',
+      'weight' => 1,
+      'filters' => array(
+        'filter_html_escape' => array(
+          'weight' => 10,
+          'status' => 1,
+        ),
+        'filter_html' => array(
+          'weight' => -10,
+          'status' => 1,
+          'settings' => array(
+            'allowed_html' => '<p>',
+          ),
+        ),
+      )
+    ));
+    $crazy_format->save();
+    // Use config to directly load the configuration and check that only enabled
+    // or customised plugins are saved to configuration.
+    $filters = \Drupal::config('filter.format.crazy')->get('filters');
+    $this->assertEqual(array('filter_html_escape', 'filter_html'), array_keys($filters));
+
+    // Disable a plugin to ensure that disabled plugins with custom settings are
+    // stored in configuration.
+    $crazy_format->setFilterConfig('filter_html_escape', array('status' => FALSE));
+    $crazy_format->save();
+    $filters = \Drupal::config('filter.format.crazy')->get('filters');
+    $this->assertEqual(array('filter_html_escape', 'filter_html'), array_keys($filters));
+
+    // Set the settings as per default to ensure that disable plugins in this
+    // state are not stored in configuration.
+    $crazy_format->setFilterConfig('filter_html_escape', array('weight' => -10));
+    $crazy_format->save();
+    $filters = \Drupal::config('filter.format.crazy')->get('filters');
+    $this->assertEqual(array('filter_html'), array_keys($filters));
+  }
+
+  /**
    * Checks if an expected violation exists in the given violations.
    *
    * @param \Symfony\Component\Validator\ConstraintViolationListInterface $violations