diff --git a/DependencyInjection/Configuration.php b/DependencyInjection/Configuration.php
index 413033d..3683c20 100644
--- a/DependencyInjection/Configuration.php
+++ b/DependencyInjection/Configuration.php
@@ -14,8 +14,14 @@ class Configuration implements ConfigurationInterface
      */
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $rootNode = $treeBuilder->root('gregwar_captcha');
+        $treeBuilder = new TreeBuilder('gregwar_captcha');
+
+        if (method_exists($treeBuilder, 'getRootNode')) {
+            $rootNode = $treeBuilder->getRootNode();
+        } else {
+            // BC for symfony/config <= 4.1
+            $rootNode = $treeBuilder->root('gregwar_captcha');
+        }
 
         $rootNode
             ->addDefaultsIfNotSet()