diff --git a/src/Executor/ReferenceExecutor.php b/src/Executor/ReferenceExecutor.php
index e4f83d5..f2e85ff 100644
--- a/src/Executor/ReferenceExecutor.php
+++ b/src/Executor/ReferenceExecutor.php
@@ -932,7 +932,7 @@ class ReferenceExecutor implements ExecutorImplementation
      *
      * @param FieldNode[]         $fieldNodes
      * @param mixed[]             $path
-     * @param mixed[]|Traversable &$results
+     * @param mixed[]|Traversable $results
      *
      * @return mixed[]|Promise
      *