diff --git a/src/EventSubscriber/LinkHeaderSubscriber.php b/src/EventSubscriber/LinkHeaderSubscriber.php
index 4edf7da4..107d3725 100644
--- a/src/EventSubscriber/LinkHeaderSubscriber.php
+++ b/src/EventSubscriber/LinkHeaderSubscriber.php
@@ -214,8 +214,8 @@ abstract class LinkHeaderSubscriber implements EventSubscriberInterface {
           // it becomes the taxonomy term's local uri.
           if ($referencedEntity->getEntityTypeId() == 'taxonomy_term') {
             $rel = "tag";
-            if ($referencedEntity->hasField('field_external_uri')) {
-              $external_uri = $referencedEntity->get('field_external_uri')->getValue();
+            if ($referencedEntity->hasField(IslandoraUtils::EXTERNAL_URI_FIELD)) {
+              $external_uri = $referencedEntity->get(IslandoraUtils::EXTERNAL_URI_FIELD)->getValue();
               if (!empty($external_uri) && isset($external_uri[0]['uri'])) {
                 $entity_url = $external_uri[0]['uri'];
               }
diff --git a/src/EventSubscriber/NodeLinkHeaderSubscriber.php b/src/EventSubscriber/NodeLinkHeaderSubscriber.php
index 443ce86f..92eac804 100644
--- a/src/EventSubscriber/NodeLinkHeaderSubscriber.php
+++ b/src/EventSubscriber/NodeLinkHeaderSubscriber.php
@@ -3,6 +3,7 @@
 namespace Drupal\islandora\EventSubscriber;
 
 use Drupal\node\NodeInterface;
+use Drupal\islandora\IslandoraUtils;
 use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 
@@ -50,8 +51,8 @@ class NodeLinkHeaderSubscriber extends LinkHeaderSubscriber implements EventSubs
     foreach ($this->utils->getMedia($node) as $media) {
       $url = $this->utils->getEntityUrl($media);
       foreach ($media->referencedEntities() as $term) {
-        if ($term->getEntityTypeId() == 'taxonomy_term' && $term->hasField('field_external_uri')) {
-          $field = $term->get('field_external_uri');
+        if ($term->getEntityTypeId() == 'taxonomy_term' && $term->hasField(IslandoraUtils::EXTERNAL_URI_FIELD)) {
+          $field = $term->get(IslandoraUtils::EXTERNAL_URI_FIELD);
           if (!$field->isEmpty()) {
             $link = $field->first()->getValue();
             $uri = $link['uri'];
diff --git a/src/Plugin/ContextReaction/JsonldTypeAlterReaction.php b/src/Plugin/ContextReaction/JsonldTypeAlterReaction.php
index 56c68cd5..ae4bc55a 100644
--- a/src/Plugin/ContextReaction/JsonldTypeAlterReaction.php
+++ b/src/Plugin/ContextReaction/JsonldTypeAlterReaction.php
@@ -6,6 +6,7 @@ use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\islandora\ContextReaction\NormalizerAlterReaction;
 use Drupal\jsonld\Normalizer\NormalizerBase;
+use Drupal\islandora\IslandoraUtils;
 
 /**
  * Alter JSON-LD Type context reaction.
@@ -46,13 +47,14 @@ class JsonldTypeAlterReaction extends NormalizerAlterReaction {
       if ($elem['@id'] === $this->getSubjectUrl($entity)) {
         foreach ($entity->get($config['source_field'])->getValue() as $type) {
           // If the configured field is using an entity reference,
-          // we will see if it uses the core config's field_external_uri.
+          // we will see if it uses the core config's
+          // IslandoraUtils::EXTERNAL_URI_FIELD.
           if (array_key_exists('target_id', $type)) {
             $target_type = $entity->get($config['source_field'])->getFieldDefinition()->getSetting('target_type');
             $referenced_entity = \Drupal::entityTypeManager()->getStorage($target_type)->load($type['target_id']);
-            if ($referenced_entity->hasField('field_external_uri') &&
-                !empty($referenced_entity->get('field_external_uri')->getValue())) {
-              foreach ($referenced_entity->get('field_external_uri')->getValue() as $value) {
+            if ($referenced_entity->hasField(IslandoraUtils::EXTERNAL_URI_FIELD) &&
+                !empty($referenced_entity->get(IslandoraUtils::EXTERNAL_URI_FIELD)->getValue())) {
+              foreach ($referenced_entity->get(IslandoraUtils::EXTERNAL_URI_FIELD)->getValue() as $value) {
                 $elem['@type'][] = $value['uri'];
               }
             }