diff --git a/composer.json b/composer.json
index 3b0e42d..79bd8a5 100644
--- a/composer.json
+++ b/composer.json
@@ -11,6 +11,7 @@
     "license": "MIT",
     "require": {
         "php": "^7.2 || ^8.0",
+        "ext-json": "*",
         "nette/php-generator": "^3.5"
     },
     "autoload": {