diff --git a/Grid/Source/Source.php b/Grid/Source/Source.php
index c96bb734..7634bf79 100755
--- a/Grid/Source/Source.php
+++ b/Grid/Source/Source.php
@@ -53,7 +53,7 @@ public function prepareRow($row)
      * @param callable $callback
      * @return $this
      */
-    public function manipulateQuery(callable $callback = null)
+    public function manipulateQuery($callback = null)
     {
         $this->prepareQueryCallback = $callback;