diff --git a/composer.json b/composer.json
index cb88213..17c5ad5 100644
--- a/composer.json
+++ b/composer.json
@@ -19,7 +19,7 @@
         "symfony/dotenv": "3.4.*|6.4.*"
     },
     "require-dev": {
-        "phpunit/phpunit": "6.*",
+        "phpunit/phpunit": "6.*|8.*",
         "squizlabs/php_codesniffer": "3.*"
     },
     "support": {