diff --git a/lib/Context/Process.php b/lib/Context/Process.php
index 3d722c8..e42b291 100644
--- a/lib/Context/Process.php
+++ b/lib/Context/Process.php
@@ -29,12 +29,14 @@ class Process implements Context {
      *
      * @param string|array $script Path to PHP script or array with first element as path and following elements options
      *     to the PHP script (e.g.: ['bin/worker', 'Option1Value', 'Option2Value'].
+     * @param string|null $cwd Working directory.
+     * @param mixed[] $env Array of environment variables.
      * @param string $binary Path to PHP binary. Null will attempt to automatically locate the binary.
      *
      * @return \Amp\Parallel\Context\Process
      */
-    public static function run($script, string $binary = null): self {
-        $process = new self($script, $binary);
+    public static function run($script, string $cwd = null, array $env = [], string $binary = null): self {
+        $process = new self($script, $cwd, $env, $binary);
         $process->start();
         return $process;
     }
@@ -42,13 +44,13 @@ class Process implements Context {
     /**
      * @param string|array $script Path to PHP script or array with first element as path and following elements options
      *     to the PHP script (e.g.: ['bin/worker', 'Option1Value', 'Option2Value'].
-     * @param string $binary Path to PHP binary. Null will attempt to automatically locate the binary.
-     * @param string $cwd Working directory.
+     * @param string|null $cwd Working directory.
      * @param mixed[] $env Array of environment variables.
+     * @param string $binary Path to PHP binary. Null will attempt to automatically locate the binary.
      *
      * @throws \Error If the PHP binary path given cannot be found or is not executable.
      */
-    public function __construct($script, string $binary = null, string $cwd = "", array $env = []) {
+    public function __construct($script, string $cwd = null, array $env = [], string $binary = null) {
         $options = [
             "html_errors" => "0",
             "display_errors" => "0",
diff --git a/lib/Worker/DefaultWorkerFactory.php b/lib/Worker/DefaultWorkerFactory.php
index 83dabb8..9c81432 100644
--- a/lib/Worker/DefaultWorkerFactory.php
+++ b/lib/Worker/DefaultWorkerFactory.php
@@ -19,10 +19,12 @@ class DefaultWorkerFactory implements WorkerFactory {
      */
     public function create(): Worker {
         if (Thread::supported()) {
-            return new WorkerThread;
+            return new WorkerThread(BasicEnvironment::class);
         }
 
         return new WorkerProcess(
+            BasicEnvironment::class,
+            [],
             \getenv("AMP_PHP_BINARY") ?: (\defined("AMP_PHP_BINARY") ? \AMP_PHP_BINARY : null)
         );
     }
diff --git a/lib/Worker/WorkerProcess.php b/lib/Worker/WorkerProcess.php
index e1a9c3b..2becb66 100644
--- a/lib/Worker/WorkerProcess.php
+++ b/lib/Worker/WorkerProcess.php
@@ -11,19 +11,19 @@ class WorkerProcess extends AbstractWorker {
     const SCRIPT_PATH = __DIR__ . "/Internal/worker-process.php";
 
     /**
-     * @param string|null $binary Path to PHP binary. Null will attempt to automatically locate the binary.
      * @param string $envClassName Name of class implementing \Amp\Parallel\Worker\Environment to instigate.
      *     Defaults to \Amp\Parallel\Worker\BasicEnvironment.
      * @param mixed[] $env Array of environment variables to pass to the worker. Empty array inherits from the current
      *     PHP process. See the $env parameter of \Amp\Process\Process::__construct().
+     * @param string|null $binary Path to PHP binary. Null will attempt to automatically locate the binary.
      *
      * @throws \Error If the PHP binary path given cannot be found or is not executable.
      */
-    public function __construct(string $binary = null, string $envClassName = BasicEnvironment::class, array $env = []) {
+    public function __construct(string $envClassName = BasicEnvironment::class, array $env = [], string $binary = null) {
         $script = [
             self::SCRIPT_PATH,
             $envClassName,
         ];
-        parent::__construct(new Process($script, $binary, __DIR__, $env));
+        parent::__construct(new Process($script, null, $env, $binary));
     }
 }