diff --git a/composer.json b/composer.json
index d2963f5..83dd986 100644
--- a/composer.json
+++ b/composer.json
@@ -17,7 +17,7 @@
         "monolog/monolog": "^2.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^7.5 || ^8.0",
+        "phpunit/phpunit": "^7.5 || ^8.0 || ^9.0",
         "orchestra/testbench": "^3.8 || ^5.0"
     },
     "autoload": {