diff --git a/composer.json b/composer.json
index 1c8147e..5111663 100644
--- a/composer.json
+++ b/composer.json
@@ -16,7 +16,8 @@
         "phpstan/phpstan-phpunit": "^1",
         "phpunit/phpunit": "^9",
         "thecodingmachine/safe": "^2",
-        "thecodingmachine/phpstan-safe-rule": "^1"
+        "thecodingmachine/phpstan-safe-rule": "^1",
+        "webmozart/assert": "^1"
     },
     "require-dev": {
         "roave/security-advisories": "dev-latest"