diff --git a/composer.json b/composer.json
index 1acd1dc..8b4152f 100644
--- a/composer.json
+++ b/composer.json
@@ -10,6 +10,6 @@
     ],
     "require": {},
     "require-dev": {
-        "phpunit/phpunit": "^5.4"
+        "phpunit/phpunit": "^9.6"
     }
 }