diff --git a/composer.json b/composer.json
index 2e97da8..16b1bad 100644
--- a/composer.json
+++ b/composer.json
@@ -43,7 +43,7 @@
         "psr/http-client-implementation": "*",
         "psr/http-factory": "^1.0",
         "psr/http-message": "^1.0 || ^2.0",
-        "sebastian/diff": "^6.0 || ^7.0 || ^8.0",
+        "sebastian/diff": "^6.0 || ^7.0 || ^8.0 || ^9.0",
         "symfony/console": "^6.4.13 || ^7.0.0 || ^8.0.0",
         "webmozart/assert": "^2.1"
     },