diff --git a/composer.json b/composer.json
index d16eaaa..14b5aec 100644
--- a/composer.json
+++ b/composer.json
@@ -19,7 +19,7 @@
     },
     "require-dev": {
         "react-parallel/stubs": "^1.2",
-        "wyrihaximus/async-test-utilities": "^5 || ^7.2",
+        "wyrihaximus/async-test-utilities": "^5 || ^7.2 || ^9.0",
         "wyrihaximus/ticking-promise": "^3"
     },
     "autoload": {