diff --git a/core/modules/rest/src/Plugin/rest/resource/EntityResource.php b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
index 75e16a7..d6fdcd1 100644
--- a/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
+++ b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
@@ -146,7 +146,7 @@ public function patch(EntityInterface $original_entity, EntityInterface $entity
     }
 
     // Overwrite the received properties.
-    $entity_keys = array_values($entity->getEntityType()->getKeys());
+    $entity_keys = $entity->getEntityType()->getKeys();
     foreach ($entity->_restSubmittedFields as $field_name) {
       $field = $entity->get($field_name);
 
@@ -154,7 +154,7 @@ public function patch(EntityInterface $original_entity, EntityInterface $entity
       // identify the entity. Therefore it does not make sense to modify any of
       // them. However, rather than throwing an error, we just ignore them as
       // long as their specified values match their current values.
-      if (in_array($field_name, $entity_keys)) {
+      if (in_array($field_name, $entity_keys, TRUE)) {
         // Unchanged values for entity keys don't need access checking.
         if ($original_entity->get($field_name)->getValue() === $entity->get($field_name)->getValue()) {
           continue;