diff --git a/lib/Doctrine/ODM/MongoDB/Persisters/CollectionPersister.php b/lib/Doctrine/ODM/MongoDB/Persisters/CollectionPersister.php
index d12696562a..68932aa73e 100644
--- a/lib/Doctrine/ODM/MongoDB/Persisters/CollectionPersister.php
+++ b/lib/Doctrine/ODM/MongoDB/Persisters/CollectionPersister.php
@@ -59,7 +59,7 @@ public function __construct(DocumentManager $dm, PersistenceBuilder $pb, UnitOfW
      * @param PersistentCollectionInterface[] $collections
      * @param array                           $options
      */
-    public function deleteAll(array $collections, array $options)
+    public function deleteAll(array $collections, array $options) : void
     {
         $parents       = [];
         $unsetPathsMap = [];
@@ -284,7 +284,7 @@ private function executeQuery(object $document, array $newObj, array $options) :
         }
     }
 
-    private function excludeSubPaths(array $paths)
+    private function excludeSubPaths(array $paths) : array
     {
         $checkedPaths = [];
         $pathsAmount  = count($paths);