diff --git a/src/Tree/RepositoryInterface.php b/src/Tree/RepositoryInterface.php
index 7bc95b5aca..a4a449eff4 100644
--- a/src/Tree/RepositoryInterface.php
+++ b/src/Tree/RepositoryInterface.php
@@ -25,7 +25,7 @@ interface RepositoryInterface extends RepositoryUtilsInterface
      * @param string $sortByField
      * @param string $direction
      *
-     * @return array<int, object>
+     * @return array<int|string, object>
      */
     public function getRootNodes($sortByField = null, $direction = 'asc');
 
@@ -37,7 +37,7 @@ public function getRootNodes($sortByField = null, $direction = 'asc');
      * @param array  $options     Options, see {@see RepositoryUtilsInterface::buildTree()} for supported keys
      * @param bool   $includeNode Flag indicating whether the given node should be included in the results
      *
-     * @return array<int, object>
+     * @return array<int|string, object>
      */
     public function getNodesHierarchy($node = null, $direct = false, array $options = [], $includeNode = false);
 
@@ -50,7 +50,7 @@ public function getNodesHierarchy($node = null, $direct = false, array $options
      * @param string|string[]      $direction   Sort order ('asc'|'desc'|'ASC'|'DESC'). If $sortByField is an array, this may also be an array with matching number of elements
      * @param bool                 $includeNode Include the root node in results?
      *
-     * @return array<int, object> List of children
+     * @return array<int|string, object> List of children
      *
      * @phpstan-param 'asc'|'desc'|'ASC'|'DESC'|array<int, 'asc'|'desc'|'ASC'|'DESC'> $direction
      */
diff --git a/src/Tree/Strategy/AbstractMaterializedPath.php b/src/Tree/Strategy/AbstractMaterializedPath.php
index 40e898b353..cf81877273 100644
--- a/src/Tree/Strategy/AbstractMaterializedPath.php
+++ b/src/Tree/Strategy/AbstractMaterializedPath.php
@@ -467,7 +467,7 @@ abstract public function removeNode($om, $meta, $config, $node);
      * @param array<string, mixed> $config       config
      * @param string               $originalPath original path of object
      *
-     * @return array|\Traversable
+     * @return array<int, object>|\Traversable<int, object>
      */
     abstract public function getChildren($om, $meta, $config, $originalPath);