diff --git a/.github/workflows/test_and_lint.yaml b/.github/workflows/test_and_lint.yaml
index 639e89a..f819724 100644
--- a/.github/workflows/test_and_lint.yaml
+++ b/.github/workflows/test_and_lint.yaml
@@ -9,8 +9,6 @@ jobs:
     strategy:
       matrix:
         include:
-          - otp: '20.3'
-            elixir: '1.5'
           - otp: '20.3'
             elixir: '1.9'
           - otp: '24.2'
diff --git a/config/config.exs b/config/config.exs
index a083314..3e87578 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -1,4 +1,4 @@
-use Mix.Config
+import Config
 
 config :extwitter, :oauth, [
    consumer_key:        System.get_env("TWITTER_CONSUMER_KEY"),
diff --git a/lib/extwitter/behaviour.ex b/lib/extwitter/behaviour.ex
index 16ed7d9..d186889 100644
--- a/lib/extwitter/behaviour.ex
+++ b/lib/extwitter/behaviour.ex
@@ -3,9 +3,12 @@ defmodule ExTwitter.Behaviour do
   A definition of the intended behavior of the core functions.
   """
 
+  @callback add_list_members(integer(), list()) :: [ExTwitter.Model.List.t()]
   @callback configure(Keyword.t()) :: :ok
   @callback configure(:global | :process, Keyword.t()) :: :ok
   @callback configure() :: Keyword.t() | nil
+  @callback create_list(Keyword.t()) :: ExTwitter.Model.List.t()
+  @callback destroy_list(Keyword.t()) :: ExTwitter.Model.List.t()
   @callback request(:get | :post, String.t()) :: map()
   @callback request(:get | :post, String.t(), Keyword.t()) :: map()
   @callback mentions_timeline :: [ExTwitter.Model.Tweet.t()]
diff --git a/mix.exs b/mix.exs
index c8a0800..5cb79e9 100644
--- a/mix.exs
+++ b/mix.exs
@@ -33,7 +33,7 @@ defmodule ExTwitter.Mixfile do
   def application do
     [
       mod: {ExTwitter, []},
-      applications: [:inets, :ssl, :crypto, :logger]
+      applications: [:inets, :ssl, :crypto, :logger, :oauther]
     ]
   end