diff --git a/src/Factory/AssetFactory.php b/src/Factory/AssetFactory.php
index 4d223c9..609bd07 100644
--- a/src/Factory/AssetFactory.php
+++ b/src/Factory/AssetFactory.php
@@ -33,7 +33,7 @@ public function addFactory(FactoryAdapterInterface $factory): void
     }
 
     /** @param array<mixed> $options */
-    public function create(string $className = null, array $options = []): AssetInterface
+    public function create(?string $className = null, array $options = []): AssetInterface
     {
         if (null === $className) {
             $className = $this->classGuesser->guessClassName($options);