diff --git a/composer.json b/composer.json
index 4e9dbad..128cd6d 100644
--- a/composer.json
+++ b/composer.json
@@ -39,6 +39,7 @@
   "extra": {
     "typo3/cms": {
       "cms-package-dir": "{$vendor-dir}/typo3/cms",
+      "extension-key": "web2pdf",
       "web-dir": "public"
     }
   }