diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
index c99106299a58..e6cf770e5883 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
@@ -1014,6 +1014,7 @@ private function addCacheSection(ArrayNodeDefinition $rootNode)
                                 ->end()
                                 ->children()
                                     ->arrayNode('adapters')
+                                        ->performNoDeepMerging()
                                         ->info('One or more adapters to chain for creating the pool, defaults to "cache.app".')
                                         ->beforeNormalization()
                                             ->always()->then(function ($values) {