diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6add618..3f5d90c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@ CHANGELOG
 
  * The component is not experimental anymore
  * Add options "env_var_name" and "debug_var_name" to `GenericRuntime` and `SymfonyRuntime`
+ * Add option "dotenv_overload" to `SymfonyRuntime`
 
 5.3.0
 -----
diff --git a/SymfonyRuntime.php b/SymfonyRuntime.php
index f957890..149e76b 100644
--- a/SymfonyRuntime.php
+++ b/SymfonyRuntime.php
@@ -40,6 +40,7 @@ class_exists(MissingDotenv::class, false) || class_exists(Dotenv::class) || clas
  *  - "prod_envs" to define the names of the production envs - defaults to ["prod"];
  *  - "test_envs" to define the names of the test envs - defaults to ["test"];
  *  - "use_putenv" to tell Dotenv to set env vars using putenv() (NOT RECOMMENDED.)
+ *  - "dotenv_overload" to tell Dotenv to override existing vars
  *
  * When the "debug" / "env" options are not defined, they will fallback to the
  * "APP_DEBUG" / "APP_ENV" environment variables, and to the "--env|-e" / "--no-debug"
@@ -84,6 +85,7 @@ class SymfonyRuntime extends GenericRuntime
      *   error_handler?: string|false,
      *   env_var_name?: string,
      *   debug_var_name?: string,
+     *   dotenv_overload?: ?bool,
      * } $options
      */
     public function __construct(array $options = [])
@@ -102,7 +104,7 @@ public function __construct(array $options = [])
             (new Dotenv($envKey, $debugKey))
                 ->setProdEnvs((array) ($options['prod_envs'] ?? ['prod']))
                 ->usePutenv($options['use_putenv'] ?? false)
-                ->bootEnv($options['project_dir'].'/'.($options['dotenv_path'] ?? '.env'), 'dev', (array) ($options['test_envs'] ?? ['test']));
+                ->bootEnv($options['project_dir'].'/'.($options['dotenv_path'] ?? '.env'), 'dev', (array) ($options['test_envs'] ?? ['test']), $options['dotenv_overload'] ?? false);
             $options['debug'] ?? $options['debug'] = '1' === $_SERVER[$debugKey];
             $options['disable_dotenv'] = true;
         } else {
diff --git a/Tests/phpt/autoload.php b/Tests/phpt/autoload.php
index 300e6bc..b109b80 100644
--- a/Tests/phpt/autoload.php
+++ b/Tests/phpt/autoload.php
@@ -2,7 +2,8 @@
 
 use Symfony\Component\Runtime\SymfonyRuntime;
 
-$_SERVER['APP_RUNTIME_OPTIONS'] = [
+$_SERVER['APP_RUNTIME_OPTIONS'] = $_SERVER['APP_RUNTIME_OPTIONS'] ?? [];
+$_SERVER['APP_RUNTIME_OPTIONS'] += [
     'project_dir' => __DIR__,
 ] + ($_SERVER['APP_RUNTIME_OPTIONS'] ?? []);
 
diff --git a/Tests/phpt/dotenv_overload.php b/Tests/phpt/dotenv_overload.php
new file mode 100644
index 0000000..4bfe6a2
--- /dev/null
+++ b/Tests/phpt/dotenv_overload.php
@@ -0,0 +1,15 @@
+<?php
+
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+$_SERVER['SOME_VAR'] = 'ccc';
+$_SERVER['APP_RUNTIME_OPTIONS'] = [
+    'dotenv_overload' => true,
+];
+
+require __DIR__.'/autoload.php';
+
+return function (Request $request, array $context) {
+    return new Response('OK Request '.$context['SOME_VAR']);
+};
diff --git a/Tests/phpt/dotenv_overload.phpt b/Tests/phpt/dotenv_overload.phpt
new file mode 100644
index 0000000..eb39d68
--- /dev/null
+++ b/Tests/phpt/dotenv_overload.phpt
@@ -0,0 +1,14 @@
+--TEST--
+Test Dotenv overload
+--SKIPIF--
+<?php require dirname(__DIR__, 6).'/vendor/autoload.php'; if (4 > (new \ReflectionMethod(\Symfony\Component\Dotenv\Dotenv::class, 'bootEnv'))->getNumberOfParameters()) die('Skip because Dotenv version is too low');
+--INI--
+display_errors=1
+--FILE--
+<?php
+
+require $_SERVER['SCRIPT_FILENAME'] = __DIR__.'/dotenv_overload.php';
+
+?>
+--EXPECTF--
+OK Request foo_bar