diff --git a/mix.exs b/mix.exs
index f4f8057..6a962a6 100644
--- a/mix.exs
+++ b/mix.exs
@@ -48,7 +48,7 @@ defmodule Ecto.ULID.Mixfile do
       {:credo, "1.7.16", only: [:dev, :test], runtime: false},
       {:dialyxir, "1.4.7", only: [:dev], runtime: false},
       {:ecto, "~> 3.2"},
-      {:ex_doc, "== 0.40.1", only: :dev, runtime: false},
+      {:ex_doc, "0.40.1", only: :dev, runtime: false},
       {:excoveralls, "0.18.5", only: :test}
     ]
   end