diff --git a/src/Symfony/Component/Finder/Iterator/SortableIterator.php b/src/Symfony/Component/Finder/Iterator/SortableIterator.php
index 479489367a..8f0090c746 100644
--- a/src/Symfony/Component/Finder/Iterator/SortableIterator.php
+++ b/src/Symfony/Component/Finder/Iterator/SortableIterator.php
@@ -73,8 +73,7 @@ class SortableIterator implements \IteratorAggregate
         } elseif (self::SORT_BY_NONE === $sort) {
             $this->sort = $order;
         } elseif (\is_callable($sort)) {
-            $this->sort = $reverseOrder ? function ($a, $b) use ($sort) { return -$sort($a, $b); }
-            : $sort;
+            $this->sort = $reverseOrder ? static function ($a, $b) use ($sort) { return -$sort($a, $b); } : $sort;
         } else {
             throw new \InvalidArgumentException('The SortableIterator takes a PHP callable or a valid built-in sort algorithm as an argument.');
         }