diff --git a/roblib_alter_solr.services.yml b/roblib_alter_solr.services.yml
index 82f65c5..ae15f05 100644
--- a/roblib_alter_solr.services.yml
+++ b/roblib_alter_solr.services.yml
@@ -1,6 +1,6 @@
 services:
   roblib_alter_solr.event_subscriber:
     class: Drupal\roblib_alter_solr\EventSubscriber\RoblibAlterSolrSubscriber
-    arguments: ['@logger.factory', '@config.factory', '@entity_type.manager']
+    arguments: ['@logger.factory', '@config.factory', '@entity_type.manager', '@solr_field.manager']
     tags:
       - { name: event_subscriber }
diff --git a/src/EventSubscriber/RoblibAlterSolrSubscriber.php b/src/EventSubscriber/RoblibAlterSolrSubscriber.php
index 84218a0..f96ef99 100644
--- a/src/EventSubscriber/RoblibAlterSolrSubscriber.php
+++ b/src/EventSubscriber/RoblibAlterSolrSubscriber.php
@@ -9,7 +9,7 @@ use Drupal\search_api_solr\Event\PostCreateIndexDocumentEvent;
 use Drupal\Core\Config\ConfigFactory;
 use Drupal\search_api\Plugin\search_api\data_type\value\TextValue;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
-
+use Drupal\search_api_solr\SolrFieldManager;
 /**
  * Allows users to combine Solr fields dynamically.
  */
@@ -36,6 +36,16 @@ final class RoblibAlterSolrSubscriber implements EventSubscriberInterface {
    */
   protected $entityTypeManager;
 
+  /**
+   * The solr field manager
+   * @var \Drupal\search_api_solr\SolrFieldManager
+   */
+  protected $fieldManager;
+
+  /**
+   * @var \Drupal\search_api_solr\SolrFieldNamesResolverInterface
+   */
+  protected SolrFieldNamesResolverInterface $fieldNameResolver;
   /**
    * Constructs a new RoblibAlterSolrSubscriber.
    *
@@ -46,10 +56,13 @@ final class RoblibAlterSolrSubscriber implements EventSubscriberInterface {
    * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entityTypeManager
    *    The EntityTypeManager.
    */
-  public function __construct(LoggerChannelFactoryInterface $logger_factory, ConfigFactory $config, EntityTypeManagerInterface $entityTypeManager) {
+
+
+  public function __construct(LoggerChannelFactoryInterface $logger_factory, ConfigFactory $config, EntityTypeManagerInterface $entityTypeManager, SolrFieldManager $fieldManager) {
     $this->logger = $logger_factory->get('roblib_alter_solr');
     $this->config = $config->get('roblib_alter_solr.settings');
     $this->entityTypeManager = $entityTypeManager;
+    $this->fieldManager = $fieldManager;
   }
 
   /**
@@ -70,7 +83,9 @@ final class RoblibAlterSolrSubscriber implements EventSubscriberInterface {
   public function onAlterSolrDocument(PostCreateIndexDocumentEvent $event) {
     $solrDocument = $event->getSolariumDocument();
     $item = $event->getSearchApiItem();
-    $pairs = $this->config->get('pairs');
+    $solr_index =$event->getIndex();
+    $defined_fields = $this->fieldManager->getFieldDefinitions($solr_index);
+    $pairs = $this->config->get('pairs') ?? [];
     $results = [];
     foreach ($pairs as $pair) {
       $dest = $pair['destination'];
@@ -108,7 +123,9 @@ final class RoblibAlterSolrSubscriber implements EventSubscriberInterface {
         $source_values = $source->getValues();
         $array_values = array_merge($source_values, $values);
         $field_name = "sm_{$field_name}";
-        $solrDocument->setField($field_name, $array_values);
+        if (isset($defined_fields[$field_name])) {
+          $solrDocument->setField($field_name, $array_values);
+        }
       }
     }
   }