diff --git a/lib/pleroma/web/plugs/ensure_host_matches_plug.ex b/lib/pleroma/web/plugs/ensure_host_matches_plug.ex
index ab2129f9e..960e86d4f 100644
--- a/lib/pleroma/web/plugs/ensure_host_matches_plug.ex
+++ b/lib/pleroma/web/plugs/ensure_host_matches_plug.ex
@@ -4,6 +4,7 @@
 
 defmodule Pleroma.Web.Plugs.EnsureHostMatchesPlug do
   @moduledoc "Ensures Host header matches instance"
+  @behaviour Plug
 
   alias Pleroma.Web.Endpoint