diff --git a/lib/Doctrine/ORM/PersistentCollection.php b/lib/Doctrine/ORM/PersistentCollection.php
index 9abea4f22..4ea56f55b 100644
--- a/lib/Doctrine/ORM/PersistentCollection.php
+++ b/lib/Doctrine/ORM/PersistentCollection.php
@@ -710,14 +710,12 @@ final class PersistentCollection extends AbstractLazyCollection implements Selec
     /**
      * @param object[] $newObjects
      *
-     * @return void
-     *
      * Note: the only reason why this entire looping/complexity is performed via `spl_object_hash`
      *       is because we want to prevent using `array_udiff()`, which is likely to cause very
      *       high overhead (complexity of O(n^2)). `array_diff_key()` performs the operation in
      *       core, which is faster than using a callback for comparisons
      */
-    private function restoreNewObjectsInDirtyCollection(array $newObjects)
+    private function restoreNewObjectsInDirtyCollection(array $newObjects) : void
     {
         $loadedObjects               = $this->collection->toArray();
         $newObjectsByOid             = \array_combine(\array_map('spl_object_hash', $newObjects), $newObjects);