diff --git a/src/Symfony/Component/Finder/Iterator/LazyIterator.php b/src/Symfony/Component/Finder/Iterator/LazyIterator.php
index 4388f4f3fd0e8..9028facf7fc3f 100644
--- a/src/Symfony/Component/Finder/Iterator/LazyIterator.php
+++ b/src/Symfony/Component/Finder/Iterator/LazyIterator.php
@@ -23,7 +23,7 @@ public function __construct(callable $iteratorFactory)
         $this->iteratorFactory = $iteratorFactory;
     }
 
-    public function getIterator()
+    public function getIterator(): \Traversable
     {
         yield from ($this->iteratorFactory)();
     }