diff --git a/composer.json b/composer.json
index 30d4438..d29b6ab 100644
--- a/composer.json
+++ b/composer.json
@@ -17,6 +17,7 @@
     "require": {
         "php": ">=7.4.0",
         "ext-intl": "*",
+        "ext-mbstring": "*",
         "nette/utils": "^3.0@dev"
     },
     "require-dev": {