diff --git a/flight/core/Loader.php b/flight/core/Loader.php
index 62e3de8..8dbf843 100644
--- a/flight/core/Loader.php
+++ b/flight/core/Loader.php
@@ -23,7 +23,7 @@ class Loader
 {
     /**
      * Registered classes.
-     * @var array<string, array{class-string, array<int, mixed>, ?callable}> $classes
+     * @var array<string, array{class-string|Closure(): object, array<int, mixed>, ?callable}> $classes
      */
     protected array $classes = [];
 
@@ -44,11 +44,11 @@ class Loader
      * @template T of object
      *
      * @param string          $name     Registry name
-     * @param class-string<T> $class    Class name or function to instantiate class
+     * @param class-string<T>|Closure(): T $class    Class name or function to instantiate class
      * @param array<int, mixed>           $params   Class initialization parameters
      * @param ?callable(T $instance): void   $callback $callback Function to call after object instantiation
      */
-    public function register(string $name, string $class, array $params = [], ?callable $callback = null): void
+    public function register(string $name, $class, array $params = [], ?callable $callback = null): void
     {
         unset($this->instances[$name]);
 
diff --git a/tests/EngineTest.php b/tests/EngineTest.php
index 0a13fcb..3f5b2f5 100644
--- a/tests/EngineTest.php
+++ b/tests/EngineTest.php
@@ -115,9 +115,8 @@ class EngineTest extends PHPUnit\Framework\TestCase
 		};
 		// doing this so we can overwrite some parts of the response
 		$engine->getLoader()->register('response', function() {
-			return new class extends \flight\net\Response {
-				public function __construct() {}
-				public function setRealHeader(string $header_string, bool $replace = true, int $response_code = 0): Response
+			return new class extends Response {
+				public function setRealHeader(string $header_string, bool $replace = true, int $response_code = 0): self
 				{
 					return $this;
 				}