diff --git a/composer.json b/composer.json
index e0c8e03..cbfba5f 100644
--- a/composer.json
+++ b/composer.json
@@ -17,7 +17,7 @@
     },
     "require": {
         "drupal/gin": "^3.0",
-        "drupal/core": "^8",
+        "drupal/core": "^8 || ^9",
         "os2forms/os2forms": "^3.0",
         "os2forms/os2forms_forloeb": "^1.8",
         "os2web/os2web_simplesaml": "8.x-dev"