diff --git a/DependencyInjection/Configuration.php b/DependencyInjection/Configuration.php
index 4bdf31a..248d606 100644
--- a/DependencyInjection/Configuration.php
+++ b/DependencyInjection/Configuration.php
@@ -23,11 +23,12 @@ public function getConfigTreeBuilder()
     {
         if (Kernel::VERSION_ID >= 40200) {
             $treeBuilder = new TreeBuilder('jb_phumbor');
+            $rootNode = $treeBuilder->getRootNode();
         } else {
             $treeBuilder = new TreeBuilder();
             $rootNode = $treeBuilder->root('jb_phumbor');
         }
-
+        
         $rootNode
             ->children()
                 ->arrayNode('server')