diff --git a/composer.json b/composer.json
index 08d31a0..90c1257 100644
--- a/composer.json
+++ b/composer.json
@@ -28,7 +28,7 @@
         }
     },
     "require-dev": {
-        "phpunit/phpunit": "^8.5.14",
+        "phpunit/phpunit": "^8.5.14 || ^9.0.0",
         "phpstan/phpstan": "0.12.81",
         "friendsofphp/php-cs-fixer": "2.18.3",
         "maglnet/composer-require-checker": "^1.1.0 || ^2.0.0 || ^3.0.0",