diff --git a/core/lib/Drupal/Core/Installer/Form/SiteSettingsForm.php b/core/lib/Drupal/Core/Installer/Form/SiteSettingsForm.php
index 0c0cb4c..6a71db4 100644
--- a/core/lib/Drupal/Core/Installer/Form/SiteSettingsForm.php
+++ b/core/lib/Drupal/Core/Installer/Form/SiteSettingsForm.php
@@ -176,8 +176,8 @@ public function submitForm(array &$form, FormStateInterface $form_state) {
       'value'    => Crypt::randomBytesBase64(55),
       'required' => TRUE,
     );
-    $settings['settings']['container_yamls'] = (object) array(
-      'value'    => ["__DIR__ . '/services.yml'"],
+    $settings['settings']['container_yamls'][0] = (object) array(
+      'value'    => "__DIR__ . '/services.yml'",
       'required' => TRUE,
     );
     // Remember the profile which was used.
diff --git a/sites/default/default.settings.php b/sites/default/default.settings.php
index e3e76ad..8702ab4 100644
--- a/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -630,7 +630,7 @@
 /**
  * Load services definition file.
  */
-$settings['container_yamls'][] = __DIR__ . '/services.yml';
+$settings['container_yamls'][0] = __DIR__ . '/services.yml';
 
 /**
  * Override the default service container class.
diff --git a/sites/example.settings.local.php b/sites/example.settings.local.php
index 34b4e19..7e2367a 100644
--- a/sites/example.settings.local.php
+++ b/sites/example.settings.local.php
@@ -32,7 +32,7 @@
 /**
  * Enable local development services.
  */
-$settings['container_yamls'][] = DRUPAL_ROOT . '/sites/development.services.yml';
+$settings['container_yamls'][0] = DRUPAL_ROOT . '/sites/development.services.yml';
 
 /**
  * Show all error messages, with backtrace information.