diff --git a/DependencyInjection/Factory/Resolver/AwsS3ResolverFactory.php b/DependencyInjection/Factory/Resolver/AwsS3ResolverFactory.php
index 8944730e8..9137c84a2 100644
--- a/DependencyInjection/Factory/Resolver/AwsS3ResolverFactory.php
+++ b/DependencyInjection/Factory/Resolver/AwsS3ResolverFactory.php
@@ -111,7 +111,8 @@ public function addConfiguration(ArrayNodeDefinition $builder)
                 ->end()
                 ->arrayNode('proxies')
                     ->defaultValue(array())
-                    ->prototype('array')->end()
+                    ->useAttributeAsKey('name')
+                    ->prototype('scalar')->end()
                 ->end()
             ->end()
         ;