diff --git a/composer.json b/composer.json
index f1d2ae5..dc41570 100644
--- a/composer.json
+++ b/composer.json
@@ -13,6 +13,6 @@
   "require": {
     "php": "^5.6|>=7.0",
     "ext-json": "*",
-    "drupal/core": "^8.5"
+      "drupal/core": "^8.5|^9.0"
   }
 }
diff --git a/csp.info.yml b/csp.info.yml
index 48ab300..15e3a15 100644
--- a/csp.info.yml
+++ b/csp.info.yml
@@ -3,6 +3,6 @@ type: module
 description: Provide Content-Security-Policy headers
 core: 8.x
 configure: csp.settings
-
+core_version_requirement: ^8 || ^9
 dependencies:
 - drupal:system (>= 8.5)