diff --git a/.travis.yml b/.travis.yml
index 46f6e50e0..8b610d76f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -24,9 +24,12 @@ matrix:
       env: SYMFONY_VERSION='~3.3.0'
     - php: '7.1'
       env: SYMFONY_VERSION='~3.4.0@dev'
+    - php: '7.1'
+      env: SYMFONY_VERSION='~4.0.0@dev'
   allow_failures:
     - php: nightly
     - env: SYMFONY_VERSION='~3.4.0@dev'
+    - env: SYMFONY_VERSION='~4.0.0@dev'
 
 before_install:
   - set -eo pipefail
diff --git a/composer.json b/composer.json
index 6ce698d47..fbe6eda22 100644
--- a/composer.json
+++ b/composer.json
@@ -32,7 +32,7 @@
         "phpspec/prophecy": "^1.6",
         "phpunit/phpunit": "^6.0",
         "symfony/phpunit-bridge": "^3.3 || ^4.0",
-        "symfony/var-dumper": "^3.2"
+        "symfony/var-dumper": "^3.2 || ^4.0"
     },
 
     "autoload": {
diff --git a/fixtures/Bridge/Symfony/Application/AppKernel.php b/fixtures/Bridge/Symfony/Application/AppKernel.php
index 68928d8ff..70d6d151a 100644
--- a/fixtures/Bridge/Symfony/Application/AppKernel.php
+++ b/fixtures/Bridge/Symfony/Application/AppKernel.php
@@ -16,6 +16,10 @@
 use Nelmio\Alice\Bridge\Symfony\NelmioAliceBundle;
 use Symfony\Bundle\FrameworkBundle\FrameworkBundle;
 use Symfony\Component\Config\Loader\LoaderInterface;
+use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
+use Symfony\Component\DependencyInjection\Compiler\PassConfig;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\HttpKernel\Kernel;
 
 class AppKernel extends Kernel
@@ -45,7 +49,7 @@ public function registerBundles()
     }
 
     /**
-     * {@inheritdoc}
+     * @inheritdoc
      */
     public function registerContainerConfiguration(LoaderInterface $loader)
     {
@@ -54,6 +58,25 @@ public function registerContainerConfiguration(LoaderInterface $loader)
         $loader->load($config);
     }
 
+    /**
+     * @inheritdoc
+     */
+    public function build(ContainerBuilder $container)
+    {
+        $container->addCompilerPass(new class implements CompilerPassInterface {
+            public function process(ContainerBuilder $container)
+            {
+                foreach ($container->getDefinitions() as $id => $definition) {
+                    $definition->setPublic(true);
+                }
+
+                foreach ($container->getAliases() as $id => $definition) {
+                    $definition->setPublic(true);
+                }
+            }
+        }, PassConfig::TYPE_OPTIMIZE);
+    }
+
     public function setConfigurationResource(string $resource)
     {
         $this->config = $resource;
diff --git a/fixtures/Bridge/Symfony/Application/config.yml b/fixtures/Bridge/Symfony/Application/config.yml
index 2fb2b7003..7cb1c4a8d 100644
--- a/fixtures/Bridge/Symfony/Application/config.yml
+++ b/fixtures/Bridge/Symfony/Application/config.yml
@@ -12,7 +12,6 @@ framework:
     router:
         resource:            ~
         strict_requirements: '%kernel.debug%'
-    trusted_proxies:         ~
     test:                    ~
     session:
         storage_id:          session.storage.mock_file
diff --git a/fixtures/Bridge/Symfony/Application/config_custom.yml b/fixtures/Bridge/Symfony/Application/config_custom.yml
index ce245d934..2ac49a911 100644
--- a/fixtures/Bridge/Symfony/Application/config_custom.yml
+++ b/fixtures/Bridge/Symfony/Application/config_custom.yml
@@ -12,7 +12,6 @@ framework:
     router:
         resource:            ~
         strict_requirements: '%kernel.debug%'
-    trusted_proxies:         ~
     test:                    ~
     session:
         storage_id:          session.storage.mock_file
diff --git a/vendor-bin/symfony/composer.json b/vendor-bin/symfony/composer.json
index 3b67ac8f0..7f9956810 100644
--- a/vendor-bin/symfony/composer.json
+++ b/vendor-bin/symfony/composer.json
@@ -1,6 +1,6 @@
 {
     "require-dev": {
-        "symfony/symfony": "^3.1",
+        "symfony/symfony": "^3.3 || ^4.0",
         "theofidry/composer-inheritance-plugin": "^1.0"
     },
     "config": {