diff --git a/core/lib/Drupal/Core/Entity/EntityStorageBase.php b/core/lib/Drupal/Core/Entity/EntityStorageBase.php
index 2ceb19c2b1..b3472a34c1 100644
--- a/core/lib/Drupal/Core/Entity/EntityStorageBase.php
+++ b/core/lib/Drupal/Core/Entity/EntityStorageBase.php
@@ -246,6 +246,7 @@ protected function doCreate(array $values) {
    * {@inheritdoc}
    */
   public function load($id) {
+    assert(!is_null($id), 'Cannot load a NULL ID.');
     $entities = $this->loadMultiple([$id]);
     return isset($entities[$id]) ? $entities[$id] : NULL;
   }