diff --git a/src/Dom/Query.php b/src/Dom/Query.php
index 3eec330..7dc5b57 100644
--- a/src/Dom/Query.php
+++ b/src/Dom/Query.php
@@ -62,7 +62,7 @@ public function setHtml($html, $charset = null)
      * @param Closure|null $callback
      * @return Collection|static
      */
-    public function getData(Closure $callback = null)
+    public function getData(?Closure $callback = null)
     {
         return $this->handleData($this->data, $callback);
     }
@@ -136,7 +136,7 @@ public function removeHead()
      * @param Closure|null $callback
      * @return QueryList
      */
-    public function query(Closure $callback = null)
+    public function query(?Closure $callback = null)
     {
         $this->data = $this->getList();
         $this->data = $this->handleData($this->data, $callback);