'contact' => [
                                'name' => 'John Doe',
                                'mail' => 'contact@example.com'
-                       ]
+                       ],
+                       'locales' => '%kernel.translator.fallbacks%'
                ];
 
                //Here we define the parameters that are allowed to configure the bundle.
                                                        ->scalarNode('mail')->cannotBeEmpty()->defaultValue($defaults['contact']['mail'])->end()
                                                ->end()
                                        ->end()
+                                       ->scalarNode('locales')->cannotBeEmpty()->defaultValue($defaults['locales'])->end()
                                ->end()
                        ->end();