diff --git a/src/Entity/Index.php b/src/Entity/Index.php
index b58744b..444fbd1 100644
--- a/src/Entity/Index.php
+++ b/src/Entity/Index.php
@@ -360,7 +360,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
    * {@inheritdoc}
    */
   public function getTrackerId() {
-    return $this->getTrackerInstance()->getConfiguration()['plugin_id'];
+    return $this->getTrackerInstance()->getPluginId();
   }
 
   /**
@@ -375,12 +375,12 @@ class Index extends ConfigEntityBase implements IndexInterface {
         );
       }
       else {
-        $tracker_settings = $this->tracker_settings[$this->getTrackerId()];
+        $tracker_settings = reset($this->tracker_settings);
       }
       $tracker_plugin_configuration = array('index' => $this) + $tracker_settings['settings'];
 
       try {
-        $this->trackerInstance = \Drupal::service('plugin.manager.search_api.tracker')->createInstance($this->getTrackerId(), $tracker_plugin_configuration);
+        $this->trackerInstance = \Drupal::service('plugin.manager.search_api.tracker')->createInstance($tracker_settings['plugin_id'], $tracker_plugin_configuration);
       } catch (PluginException $pe) {
         $args['@tracker'] = $tracker_settings['plugin_id'];
         $args['%index'] = $this->label();
@@ -1222,8 +1222,18 @@ class Index extends ConfigEntityBase implements IndexInterface {
    *   The previous version of the index.
    */
   protected function reactToProcessorChanges(IndexInterface $original) {
-    $original_settings = $original->getProcessorSettings();
-    $new_settings = $this->getProcessorSettings();
+    $orginal_processors = $original->getProcessors();
+    $new_processors = $this->getProcessors();
+
+    $new_settings = array();
+    $original_settings = array();
+
+    foreach ($orginal_processors as $k => $processor) {
+      $original_settings[$k] = $processor->getConfiguration();
+    }
+    foreach ($new_processors as $k => $processor) {
+      $new_settings[$k] = $processor->getConfiguration();
+    }
 
     // Only actually do something when the processor settings are changed.
     if ($original_settings != $new_settings) {
diff --git a/src/Item/Field.php b/src/Item/Field.php
index 97637ad..abbe268 100644
--- a/src/Item/Field.php
+++ b/src/Item/Field.php
@@ -439,8 +439,7 @@ class Field implements \IteratorAggregate, FieldInterface {
    */
   public function getBoost() {
     if (!isset($this->boost)) {
-      $fields = $this->index->getFieldSettings();
-      $this->boost = isset($fields[$this->fieldIdentifier]['boost']) ? (float) $fields[$this->fieldIdentifier]['boost'] : 1.0;
+      $this->boost = 1.0;
     }
     return $this->boost;
   }
diff --git a/src/Tests/Processor/ProcessorIntegrationTest.php b/src/Tests/Processor/ProcessorIntegrationTest.php
index 92e590f..912e9e4 100644
--- a/src/Tests/Processor/ProcessorIntegrationTest.php
+++ b/src/Tests/Processor/ProcessorIntegrationTest.php
@@ -173,7 +173,7 @@ class ProcessorIntegrationTest extends WebTestBase {
    */
   public function checkLanguageIntegration() {
     $index = $this->loadIndex();
-    $processors = $index->getProcessorSettings();
+    $processors = $index->getProcessors();
     $this->assertTrue(!empty($processors['language']), 'The "language" processor is enabled by default.');
     unset($processors['language']);
     $index->setProcessorSettings($processors)->save();
diff --git a/src/Tests/Processor/ProcessorTestBase.php b/src/Tests/Processor/ProcessorTestBase.php
index abb60e6..cc93553 100644
--- a/src/Tests/Processor/ProcessorTestBase.php
+++ b/src/Tests/Processor/ProcessorTestBase.php
@@ -9,6 +9,7 @@ namespace Drupal\search_api\Tests\Processor;
 
 use Drupal\search_api\Entity\Index;
 use Drupal\search_api\Entity\Server;
+use Drupal\search_api\Item\Field;
 use Drupal\search_api\Utility;
 use Drupal\system\Tests\Entity\EntityUnitTestBase;
 
@@ -106,22 +107,23 @@ abstract class ProcessorTestBase extends EntityUnitTestBase {
       ),
     ));
     $this->index->setServer($this->server);
-    $this->index->setFieldSettings(array(
-      'subject' => array(
-        'label' => 'Subject',
-        'type' => 'text',
-        'datasource_id' => 'entity:comment',
-        'property_path' => 'subject',
-      ),
-      'title' => array(
-        'label' => 'Title',
-        'type' => 'text',
-        'datasource_id' => 'entity:node',
-        'property_path' => 'title',
-      ),
-    ));
+
+    $subject_field = new Field($this->index, 'subject');
+    $subject_field->setType('text');
+    $subject_field->setLabel('Subject');
+    $subject_field->setDatasourceId('entity:comment');
+    $subject_field->setPropertyPath('subject');
+    $this->index->addField($subject_field);
+
+    $title_field = new Field($this->index, 'title');
+    $title_field->setType('text');
+    $title_field->setLabel('Title');
+    $title_field->setDatasourceId('entity:node');
+    $title_field->setPropertyPath('title');
+    $this->index->addField($title_field);
+
     if ($processor) {
-      $this->index->setProcessorSettings(array(
+      $this->index->set('processor_settings', array(
         $processor => array(
           'plugin_id' => $processor,
           'weights' => array(),
diff --git a/src/Tests/Processor/RenderedItemTest.php b/src/Tests/Processor/RenderedItemTest.php
index 8a920e4..20157c7 100644
--- a/src/Tests/Processor/RenderedItemTest.php
+++ b/src/Tests/Processor/RenderedItemTest.php
@@ -10,6 +10,7 @@ namespace Drupal\search_api\Tests\Processor;
 use Drupal\Core\TypedData\DataDefinition;
 use Drupal\node\Entity\Node;
 use Drupal\node\Entity\NodeType;
+use Drupal\search_api\Item\FieldInterface;
 use Drupal\search_api\Utility;
 use Drupal\user\Entity\Role;
 use Drupal\user\Entity\User;
@@ -115,6 +116,14 @@ class RenderedItemTest extends ProcessorTestBase {
   }
 
   /**
+   * Tests that the processor is added correctly.
+   */
+  public function testAddProcessor() {
+    $processors = $this->index->getProcessors();
+    $this->assertTrue(array_key_exists('rendered_item', $processors), 'Processor successfully added.');
+  }
+
+  /**
    * Tests whether the rendered_item field is correctly filled by the processor.
    */
   public function testPreprocessIndexItems() {