diff --git a/src/Core/Config/ConfigLoader.php b/src/Core/Config/ConfigLoader.php
index caa50201a..38d088df2 100644
--- a/src/Core/Config/ConfigLoader.php
+++ b/src/Core/Config/ConfigLoader.php
@@ -10,6 +10,7 @@ use SilverStripe\Config\Collections\ConfigCollectionInterface;
 class ConfigLoader
 {
     /**
+     * @internal
      * @var self
      */
     private static $instance;
diff --git a/src/Core/Manifest/ClassLoader.php b/src/Core/Manifest/ClassLoader.php
index d781f1b16..8561001ee 100644
--- a/src/Core/Manifest/ClassLoader.php
+++ b/src/Core/Manifest/ClassLoader.php
@@ -13,6 +13,7 @@ class ClassLoader
 {
 
     /**
+     * @internal
      * @var ClassLoader
      */
     private static $instance;