diff --git a/composer.json b/composer.json
index d9e0ca64..36a3aedb 100644
--- a/composer.json
+++ b/composer.json
@@ -42,7 +42,7 @@
         "microsoft/tolerant-php-parser": "^0.1.2"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.5",
+        "phpunit/phpunit": "^13.0",
         "google/gax": "^1.37.0"
     },
     "scripts": {