diff --git a/composer.json b/composer.json
index 7be6538..9efb557 100644
--- a/composer.json
+++ b/composer.json
@@ -32,7 +32,7 @@
         "guzzlehttp/psr7": "^1.8.2"
     },
     "require-dev": {
-        "phpunit/phpunit": "^4.8",
+        "phpunit/phpunit": "^13.0",
         "squizlabs/php_codesniffer": "~2.6",
         "friendsofphp/php-cs-fixer": "~2.12"
     },