diff --git a/lib/tortoise311.ex b/lib/tortoise311.ex
index 7901249..4180745 100644
--- a/lib/tortoise311.ex
+++ b/lib/tortoise311.ex
@@ -78,7 +78,7 @@ defmodule Tortoise311 do
   it is really easy to hit the maximum byte limit. Solving this is
   easy, just add a `:` before the client id such as `:Example`.
   """
-  @type client_id() :: atom() | String.t()
+  @type client_id() :: atom() | String.t() | {String.t(), atom()}
 
   @typedoc """
   A 16-bit number identifying a message in a message exchange.
diff --git a/lib/tortoise311/package/connect.ex b/lib/tortoise311/package/connect.ex
index 62e95b1..b5def4c 100644
--- a/lib/tortoise311/package/connect.ex
+++ b/lib/tortoise311/package/connect.ex
@@ -14,6 +14,7 @@ defmodule Tortoise311.Package.Connect do
             clean_session: boolean(),
             keep_alive: non_neg_integer(),
             client_id: Tortoise311.client_id(),
+            discriminator: atom(),
             will: Package.Publish.t() | nil
           }
 
@@ -26,6 +27,7 @@ defmodule Tortoise311.Package.Connect do
             clean_session: true,
             keep_alive: 60,
             client_id: nil,
+            discriminator: nil,
             will: nil
 
   @spec decode(binary()) :: t
@@ -102,6 +104,10 @@ defmodule Tortoise311.Package.Connect do
       encode(%Package.Connect{t | client_id: Atom.to_string(client_id)})
     end
 
+    def encode(%Package.Connect{client_id: {client_id, _discriminator}} = t) do
+      encode(%Package.Connect{t | client_id: client_id})
+    end
+
     defp protocol_header(%{protocol: protocol, protocol_version: version}) do
       [Package.length_encode(protocol), version]
     end