diff --git a/DependencyInjection/Configuration.php b/DependencyInjection/Configuration.php
index 773f413..cb1f824 100644
--- a/DependencyInjection/Configuration.php
+++ b/DependencyInjection/Configuration.php
@@ -23,8 +23,8 @@ class Configuration implements ConfigurationInterface
      */
     public function getConfigTreeBuilder()
     {
-        $treeBuilder = new TreeBuilder();
-        $rootNode = $treeBuilder->root('api_postcode');
+        $treeBuilder = new TreeBuilder('api_postcode');
+        $rootNode = $treeBuilder->getRootNode();
 
         $rootNode->children()
                 ->scalarNode('token')->isRequired()->end()
diff --git a/Resources/config/services.yml b/Resources/config/services.yml
index 1f814a3..b2287e6 100644
--- a/Resources/config/services.yml
+++ b/Resources/config/services.yml
@@ -3,3 +3,6 @@ services:
       class: ApiPostcode\Client\PostcodeClient
       arguments:
           - "%api_postcode_key%"
+
+    ApiPostcode\Client\PostcodeClient:
+      alias: api.postcode
diff --git a/composer.json b/composer.json
index a64fa4e..b3ab297 100644
--- a/composer.json
+++ b/composer.json
@@ -13,7 +13,7 @@
     ],
     "require": {
         "php": ">=5.4",
-        "symfony/framework-bundle": "^2.7 || ^3.0",
+        "symfony/framework-bundle": "^2.7 || ^3.0 || ^4.0 || ^5.0",
         "api-postcode/php-client": "^1.0"
     },
     "require-dev": {