diff --git a/composer.json b/composer.json
index 19e7689c..f8582e6e 100644
--- a/composer.json
+++ b/composer.json
@@ -65,7 +65,7 @@
     "require-dev": {
         "ext-zip": "*",
         "ext-gd": "*",
-        "phpunit/phpunit": "^4.8.36 || ^7.0",
+        "phpunit/phpunit": "^4.8.36 || ^7.0 || ^9.0",
         "squizlabs/php_codesniffer": "^2.9 || ^3.5",
         "friendsofphp/php-cs-fixer": "^2.2",
         "phpmd/phpmd": "2.*",