diff --git a/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/EntityReferenceNotNullConstraintValidator.php b/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/EntityReferenceNotNullConstraintValidator.php
index b340bd6..22b7071 100644
--- a/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/EntityReferenceNotNullConstraintValidator.php
+++ b/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/EntityReferenceNotNullConstraintValidator.php
@@ -28,7 +28,7 @@ public function validate($value, Constraint $constraint) {
       if ($item->isEmpty()) {
         continue;
       }
-      if (!$item->target_id && !$item->entity->isNew()) {
+      if ($item->target_id === NULL && !$item->entity->isNew()) {
         $this->context->addViolation($constraint->message);
         return;
       }