diff --git a/composer.json b/composer.json
index 6d01aecd7..27ea75402 100644
--- a/composer.json
+++ b/composer.json
@@ -13,7 +13,7 @@
         "ext-json": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "^8.5.13",
+        "phpunit/phpunit": "^9.6.4",
         "laminas/laminas-diactoros": "^2.4.1",
         "phpstan/phpstan": "^0.12.57",
         "phpstan/phpstan-phpunit": "^0.12.16",