diff --git a/tests/phpunit/scheduler/AsyncPoolTest.php b/tests/phpunit/scheduler/AsyncPoolTest.php
index 53ec15c12..88985cc39 100644
--- a/tests/phpunit/scheduler/AsyncPoolTest.php
+++ b/tests/phpunit/scheduler/AsyncPoolTest.php
@@ -71,6 +71,7 @@ class AsyncPoolTest extends TestCase{
 	}
 
 	public function testThreadSafeSetResult() : void{
+		/** @phpstan-var PromiseResolver<ThreadSafeArray<array-key, mixed>> $resolver */
 		$resolver = new PromiseResolver();
 		$resolver->getPromise()->onCompletion(
 			function(ThreadSafeArray $result) : void{