diff --git a/src/HandlerResolver.php b/src/HandlerResolver.php
index 1c7442e..d6553ba 100644
--- a/src/HandlerResolver.php
+++ b/src/HandlerResolver.php
@@ -108,12 +108,10 @@ private function symfonyContainer(?string $bootstrapFile = null): ContainerInter
                 ));
             }
 
-            $projectDir = getenv('LAMBDA_TASK_ROOT') ?: null;
-
             // Use the Symfony Runtime component to resolve the closure and get the PSR-11 container
             $options = $_SERVER['APP_RUNTIME_OPTIONS'] ?? [];
-            if ($projectDir) {
-                $options['project_dir'] = $projectDir;
+            if (! isset($options['project_dir'])) {
+                $options['project_dir'] = dirname(__DIR__, 4);
             }
 
             $runtimeClass = $_SERVER['APP_RUNTIME'] ?? $_ENV['APP_RUNTIME'] ?? BrefRuntime::class;