diff --git a/README.md b/README.md
index 92d946ba53d2e828d0c30fd99e356492762bb27c..ccd35ce02f713e9a73ac76505cb8296406a8f4fa 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,7 @@ The extension defines the following parser functions and variables:
 The extension hides the sidebar for not logged in users.
 
 It also provides two css depending on the status of the user :
-* ``MediaWiki:NotLoggedIn.css``
+* ``MediaWiki:NotLoggedIn.css`` (which should be listed in ``$wgWhitelistRead``)
 * ``MediaWiki:LoggedIn.css``
 
 ## Installation