diff --git a/mix.exs b/mix.exs
index e23383d..d5a5a71 100644
--- a/mix.exs
+++ b/mix.exs
@@ -51,7 +51,8 @@ defmodule TwentyFortyEight.MixProject do
       {:jason, "~> 1.2"},
       {:dns_cluster, "~> 0.1.1"},
       {:plug_cowboy, "~> 2.5"},
-      {:credo, "~> 1.7", only: [:dev, :test], runtime: false}
+      {:credo, "~> 1.7", only: [:dev, :test], runtime: false},
+      {:dialyxir, "~> 1.4", only: [:dev, :test], runtime: false}
     ]
   end