diff --git a/DependencyInjection/Configuration.php b/DependencyInjection/Configuration.php
index d82158c..5177ddf 100644
--- a/DependencyInjection/Configuration.php
+++ b/DependencyInjection/Configuration.php
@@ -120,6 +120,7 @@ public function addKeysConfig($key, $default = [])
             ->prototype('scalar')
                 ->isRequired()
             ->end()
+            ->normalizeKeys(false)
             ->defaultValue($default);
 
         return $node;