diff --git a/composer.json b/composer.json
index f1d20a9..966bcd9 100644
--- a/composer.json
+++ b/composer.json
@@ -49,7 +49,8 @@
         "symfony/yaml": "6.0.*",
         "techtube/bookinfo": "1.*",
         "twig/extra-bundle": "^2.12|^3.0",
-        "twig/twig": "^2.12|^3.0"
+        "twig/twig": "^2.12|^3.0",
+        "ext-mbstring": "*"
     },
     "config": {
         "allow-plugins": {