diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3e295565c..a685ac71f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,8 @@
-## v0.4.2
+## v0.4.2 (2014-08-31)
 
 * Enhancements
   * Add task `hex.user whoami` that prints the locally authorized user
+  * Add task `hex.user deauth` to deauthorize the local user
   * Rename environment variable `HEX_URL` to `HEX_API` to not confuse it with `HEX_CDN`
 
 * Bug fixes
diff --git a/lib/hex/registry.ex b/lib/hex/registry.ex
index 5537e1371..79f8dfa84 100644
--- a/lib/hex/registry.ex
+++ b/lib/hex/registry.ex
@@ -119,7 +119,7 @@ defmodule Hex.Registry do
     case :ets.lookup(get_tid(), {package, version}) do
       [] ->
         nil
-      [{{^package, ^version}, [_, checksum | _]}] when is_nil(checksum) or is_binary(checksum) ->
+      [{{^package, ^version}, [_, checksum | _]}] when nil?(checksum) or is_binary(checksum) ->
         checksum
     end
   end
diff --git a/lib/hex/util.ex b/lib/hex/util.ex
index 0c8f23d0d..773ec721d 100644
--- a/lib/hex/util.ex
+++ b/lib/hex/util.ex
@@ -191,7 +191,7 @@ defmodule Hex.Util do
     do: binary
   defp binarify(number) when is_number(number),
     do: number
-  defp binarify(atom) when is_nil(atom) or is_boolean(atom),
+  defp binarify(atom) when nil?(atom) or is_boolean(atom),
     do: atom
   defp binarify(atom) when is_atom(atom),
     do: Atom.to_string(atom)
diff --git a/lib/mix/tasks/hex/user.ex b/lib/mix/tasks/hex/user.ex
index 2ea8a4e18..7b1f4ba24 100644
--- a/lib/mix/tasks/hex/user.ex
+++ b/lib/mix/tasks/hex/user.ex
@@ -22,10 +22,16 @@ defmodule Mix.Tasks.Hex.User do
 
   `mix hex.user auth`
 
-  ### Update user options
+  ### Deauthorize the user
 
-  `mix hex.user update`
+  Deauthorizes the user from the local machine by removing the API key from the
+  hex config.
+
+  `mix hex.user deauth`
 
+  ### Update user configuration
+
+  `mix hex.user update`
   """
 
   @switches [clean_pass: :boolean]
@@ -89,7 +95,7 @@ defmodule Mix.Tasks.Hex.User do
     new_email    = Mix.shell.prompt("Email:")             |> String.strip |> nillify
     new_password = Util.password_get("Password:", clean?) |> String.strip |> nillify
 
-    unless is_nil(new_password) do
+    unless nil?(new_password) do
       confirm = Util.password_get("Password (confirm):", clean?) |> String.strip |> nillify
       if password != confirm do
         Mix.raise "Entered passwords do not match"
@@ -118,7 +124,7 @@ defmodule Mix.Tasks.Hex.User do
     email    = Mix.shell.prompt("Email:")     |> String.strip
     password = Util.password_get("Password:", clean?) |> String.strip
 
-    unless is_nil(password) do
+    unless nil?(password) do
       confirm = Util.password_get("Password (confirm):", clean?) |> String.strip
       if password != confirm do
         Mix.raise "Entered passwords do not match"
diff --git a/mix.exs b/mix.exs
index fdf33898c..125e339da 100644
--- a/mix.exs
+++ b/mix.exs
@@ -3,8 +3,8 @@ defmodule Hex.Mixfile do
 
   def project do
     [app: :hex,
-     version: "0.4.2-dev",
-     elixir: "~> 1.0.0-rc1",
+     version: "0.4.2",
+     elixir: "~> 0.15.0 or ~> 1.0.0-rc1",
      aliases: aliases,
      deps: deps]
   end