diff --git a/audiofix_ror.module b/audiofix_ror.module
index f5c6c0b..b5b2636 100644
--- a/audiofix_ror.module
+++ b/audiofix_ror.module
@@ -1,4 +1,7 @@
 <?php
+
+const PARAGRAPH = 'audio';
+const LINKFIELD = 'field_audio_link';
 function isArchive(string $url): bool {
 	$pos = strpos($url, "archive.org/");
 	if($pos === FALSE) {
@@ -28,18 +31,18 @@ function normalizeArchive(string $url) {
  */
 function audiofix_ror_paragraph_presave(Drupal\Core\Entity\EntityInterface $entity) {
     // per i paragraph, getType() === bundle(). 
-    if($entity->bundle() !== 'audio') { // audio e' il nome del nostro paragraph type
+    if($entity->bundle() !== PARAGRAPH) { // audio e' il nome del nostro paragraph type
         return;
     }
     // campi utili: field_audio_link e field_durata
-    $link = $entity->get('field_audio_link')->getValue();
+    $link = $entity->get(LINKFIELD)->getValue();
     if(count($link) == 0) { return; }
     $link = $link[0]['uri'];
     if(is_string($link) && isArchive($link)) {
         $norm = normalizeArchive($link);
         if($norm !== $link) {
             \Drupal::logger('audiofix_ror')->notice('Aggiornato da :old a :new', array(":old" => $link, ":new" => $norm));
-            $entity->set('field_audio_link', $norm);
+            $entity->set(LINKFIELD, $norm);
         }
     }
 }