diff --git a/modules/grist.nix b/modules/grist.nix
index c7f5377..a666845 100644
--- a/modules/grist.nix
+++ b/modules/grist.nix
@@ -43,6 +43,7 @@ with lib;
             # Force users to login (disable anonymous access)
             # GRIST_FORCE_LOGIN: true
             # Base URL Grist redirects to when navigating. Change this to your domain.
+            GRIST_OIDC_SP_HOST = "https://${dn}";
             APP_HOME_URL = "https://${dn}";
             # Default email for the "Admin" account
             GRIST_DEFAULT_EMAIL = "chris@tfcconnection.org";