diff --git a/src/Fortress/ServerSideValidator.php b/src/Fortress/ServerSideValidator.php
index bc1458a..e77f44e 100644
--- a/src/Fortress/ServerSideValidator.php
+++ b/src/Fortress/ServerSideValidator.php
@@ -86,7 +86,7 @@ public function data(): array
      *
      * @return mixed[]|bool
      */
-    public function errors(string $field = null)
+    public function errors(string|null $field = null)
     {
         if ($field !== null) {
             return isset($this->errors[$field]) ? $this->errors[$field] : false;