diff --git a/lib/exw3.ex b/lib/exw3.ex
index cbfea36..020a841 100644
--- a/lib/exw3.ex
+++ b/lib/exw3.ex
@@ -40,6 +40,8 @@ defmodule ExW3 do
     @unit_map
   end
 
+  @spec to_wei(integer(), keyword()) :: integer()
+  @doc "Converts the value to whatever unit key is provided. See unit map for details."
   def to_wei(num, key) do
     if @unit_map[key] do
       num * @unit_map[key]
@@ -48,6 +50,8 @@ defmodule ExW3 do
     end
   end
 
+  @spec from_wei(integer(), keyword()) :: integer()
+  @doc "Converts the value to whatever unit key is provided. See unit map for details."  
   def from_wei(num, key) do
     if @unit_map[key] do
       num / @unit_map[key]
diff --git a/mix.exs b/mix.exs
index 917ab12..907cf88 100644
--- a/mix.exs
+++ b/mix.exs
@@ -4,7 +4,7 @@ defmodule ExW3.MixProject do
   def project do
     [
      app: :exw3,
-     version: "0.4.1",
+     version: "0.4.2",
      elixir: "~> 1.7.2",
      build_embedded: Mix.env == :prod,
      start_permanent: Mix.env == :prod,