diff --git a/lib/expo/message.ex b/lib/expo/message.ex
index 8af86a4..19466b8 100644
--- a/lib/expo/message.ex
+++ b/lib/expo/message.ex
@@ -42,12 +42,9 @@ defmodule Expo.Message do
   """
   @type t :: Singular.t() | Plural.t()
 
-  @typedoc """
-  The key that can be used to identify a message.
-
-  See `key/1`.
-  """
-  @opaque key :: Singular.key() | Plural.key()
+  @typep key ::
+           {msgctxt :: String.t(), msgid :: String.t()}
+           | {msgctxt :: String.t(), msgid :: String.t()}
 
   @doc """
   Returns a "key" that can be used to identify a message.
diff --git a/lib/expo/message/plural.ex b/lib/expo/message/plural.ex
index b3e9023..2ad8433 100644
--- a/lib/expo/message/plural.ex
+++ b/lib/expo/message/plural.ex
@@ -19,15 +19,8 @@ defmodule Expo.Message.Plural do
   """
   @type block :: :msgid | {:msgstr, non_neg_integer()} | :msgctxt | :msgid_plural
 
-  @typedoc """
-  Metadata for this struct.
-  """
-  @opaque meta :: %{optional(:source_line) => %{block() => non_neg_integer()}}
-
-  @typedoc """
-  The key that identifies this message.
-  """
-  @opaque key :: {msgctxt :: String.t(), msgid :: String.t()}
+  @typep meta :: %{optional(:source_line) => %{block() => non_neg_integer()}}
+  @typep key :: {msgctxt :: String.t(), msgid :: String.t()}
 
   @typedoc """
   The type for this struct.
diff --git a/lib/expo/message/singular.ex b/lib/expo/message/singular.ex
index 1387257..863566b 100644
--- a/lib/expo/message/singular.ex
+++ b/lib/expo/message/singular.ex
@@ -18,15 +18,8 @@ defmodule Expo.Message.Singular do
   """
   @type block :: :msgid | :msgstr | :msgctxt
 
-  @typedoc """
-  Metadata for this struct.
-  """
-  @opaque meta :: %{optional(:source_line) => %{block() => non_neg_integer()}}
-
-  @typedoc """
-  The key that identifies this message.
-  """
-  @opaque key :: {msgctxt :: String.t(), msgid :: String.t()}
+  @typep meta :: %{optional(:source_line) => %{block() => non_neg_integer()}}
+  @typep key :: {msgctxt :: String.t(), msgid :: String.t()}
 
   @typedoc """
   The type for this struct.
diff --git a/lib/expo/plural_forms.ex b/lib/expo/plural_forms.ex
index b54e346..abc76c0 100644
--- a/lib/expo/plural_forms.ex
+++ b/lib/expo/plural_forms.ex
@@ -25,18 +25,12 @@ defmodule Expo.PluralForms do
           plural: plural_ast()
         }
 
-  @typedoc """
-  The AST of a plural forms expression.
-
-  This is evaluated internally to determine the plural form for a given number
-  using `index/2`, and is not meant to be inspected directly.
-  """
-  @opaque plural_ast() ::
-            :n
-            | integer()
-            | {:!= | :> | :< | :== | :% | :<= | :>= | :&& | :||, plural_ast(), plural_ast()}
-            | {:if, plural_ast(), plural_ast(), plural_ast()}
-            | {:paren, plural_ast()}
+  @typep plural_ast() ::
+           :n
+           | integer()
+           | {:!= | :> | :< | :== | :% | :<= | :>= | :&& | :||, plural_ast(), plural_ast()}
+           | {:if, plural_ast(), plural_ast(), plural_ast()}
+           | {:paren, plural_ast()}
 
   @doc """
   Parses a plural forms string into a `t:t/0` struct.