diff --git a/nixos/modules/services/web-apps/mastodon.nix b/nixos/modules/services/web-apps/mastodon.nix
index 1e3c7e53c175..8208c85bfd70 100644
--- a/nixos/modules/services/web-apps/mastodon.nix
+++ b/nixos/modules/services/web-apps/mastodon.nix
@@ -92,6 +92,7 @@ let
 
   mastodonEnv = pkgs.writeShellScriptBin "mastodon-env" ''
     set -a
+    export RAILS_ROOT="${cfg.package}"
     source "${envFile}"
     source /var/lib/mastodon/.secrets_env
     eval -- "\$@"