diff -u b/core/lib/Drupal/Core/Config/DatabaseStorage.php b/core/lib/Drupal/Core/Config/DatabaseStorage.php
--- b/core/lib/Drupal/Core/Config/DatabaseStorage.php
+++ b/core/lib/Drupal/Core/Config/DatabaseStorage.php
@@ -53,14 +53,14 @@
   /**
    * Implements StorageInterface::encode().
    */
-  function encode($data) {
+  public function encode($data) {
     return serialize($data);
   }
 
   /**
    * Implements StorageInterface::decode().
    */
-  function decode($raw) {
+  public function decode($raw) {
     return unserialize($raw);
   }
 
diff -u b/core/lib/Drupal/Core/Config/FileStorage.php b/core/lib/Drupal/Core/Config/FileStorage.php
--- b/core/lib/Drupal/Core/Config/FileStorage.php
+++ b/core/lib/Drupal/Core/Config/FileStorage.php
@@ -53,8 +53,8 @@
   /**
    * Sets the path to the configuration file.
    */
-  public function setFilePath($directory) {
-    $this->filePath = $directory . '/' . $this->name . '.' . $this->getFileExtension();
+  private function setFilePath($directory) {
+    $this->filePath = $directory . '/' . $this->name . '.' . $this::getFileExtension();
   }
 
   /**
@@ -102,16 +102,16 @@
   /**
    * Implements StorageInterface::encode().
    */
-  public function encode($data) {
-    // Once the array nesting level reaches 5 switch to inline YAML for
-    // readability.
-    return Yaml::dump($data, 5);
+  private function encode($data) {
+    // The level where you switch to inline YAML is set to PHP_INT_MAX to ensure
+    // this does not occur.
+    return Yaml::dump($data, PHP_INT_MAX);
   }
 
   /**
    * Implements StorageInterface::decode().
    */
-  public function decode($raw) {
+  private function decode($raw) {
     if (empty($raw)) {
       return array();
     }