diff --git a/core/lib/Drupal/Core/Config/StorableConfigBase.php b/core/lib/Drupal/Core/Config/StorableConfigBase.php
index f2920a7..11ed8bd 100644
--- a/core/lib/Drupal/Core/Config/StorableConfigBase.php
+++ b/core/lib/Drupal/Core/Config/StorableConfigBase.php
@@ -223,6 +223,10 @@ protected function castValue($key, $value) {
               break;
 
             case 'value':
+              // The PHP documentation notes that "Be careful when sorting
+              // arrays with mixed types values because sort() can produce
+              // unpredictable results". Fortunately we have already cast all
+              // the values to the same type using configuration schema.
               sort($value);
               break;