diff --git a/composer.json b/composer.json
index 32a0165..2b77a6a 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,8 @@
 		}
 	},
     "require-dev": {
-        "phpunit/phpunit": "^8",
+		"ext-json": "*",
+		"phpunit/phpunit": "^8",
 		"spatie/phpunit-snapshot-assertions": "^2.2.0"
     },
 	"scripts": {