diff --git a/composer.json b/composer.json
index 0446172..a4bc6b1 100644
--- a/composer.json
+++ b/composer.json
@@ -23,6 +23,7 @@
   "minimum-stability": "dev",
   "require": {
     "php": ">=7.2.0",
+    "drupal/core": "^8.8 || ^9",
     "league/commonmark": "^1.0.0"
   },
   "suggest": {