diff --git a/composer.json b/composer.json
index 6755561..4d69fe4 100644
--- a/composer.json
+++ b/composer.json
@@ -31,7 +31,7 @@
         "symfony/options-resolver": "^3.1"
     },
     "require-dev": {
-        "phpunit/phpunit": "^4.7|^5.5",
+        "phpunit/phpunit": "^8.3.3",
         "friendsofphp/php-cs-fixer": "^2.0",
         "sllh/php-cs-fixer-styleci-bridge": "^2.1"
     },