diff --git a/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php b/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php
index 127c188..ef936cc 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php
@@ -305,7 +305,9 @@ protected function doPostSave(EntityInterface $entity, $update) {
 
     // The revision is stored, it should no longer be marked as new now.
     if ($this->entityType->isRevisionable()) {
-      $entity->resetOriginalRevisionId();
+      if ($entity instanceof OriginalRevisionIdInterface) {
+        $entity->resetOriginalRevisionId();
+      }
       $entity->setNewRevision(FALSE);
     }
   }
diff --git a/core/lib/Drupal/Core/Entity/OriginalRevisionIdInterface.php b/core/lib/Drupal/Core/Entity/OriginalRevisionIdInterface.php
index 4cacc4e..111f642 100644
--- a/core/lib/Drupal/Core/Entity/OriginalRevisionIdInterface.php
+++ b/core/lib/Drupal/Core/Entity/OriginalRevisionIdInterface.php
@@ -7,12 +7,7 @@
   /**
    * Gets the original revision identifier of the entity.
    *
-   * After calling ::setNewRevision, the revision identifier will be unset to
-   * enforce the creation of a new revision identifier on save and
-   * ::getRevisionId will not be able to return the revision identifier, for
-   * which the entity has been loaded, but ::getOriginalRevisionId will.
-   *
-   * @return
+   * @return int
    *   The original revision identifier of the entity, or NULL if the entity
    *   does not have a revision identifier.
    */
@@ -21,7 +16,7 @@ public function getOriginalRevisionId();
   /**
    * Resets the original revision identifier after the entity got a new one.
    *
-   * After the entity has been saved, the storage should call this function to
+   * After the entity has been saved, the storage must call this function to
    * set the original revision identifier to the new one, the entity received
    * after it has been saved.
    */