diff --git a/lib/earmark/error.ex b/lib/earmark/error.ex
index 468e4309..cd2c50b2 100644
--- a/lib/earmark/error.ex
+++ b/lib/earmark/error.ex
@@ -4,6 +4,8 @@ defmodule Earmark.Error do
 
   defexception [:message]
 
+  @type t :: %__MODULE__{message: binary()}
+
   @doc false
   def exception(msg), do: %__MODULE__{message: msg}