diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e74f2f578..1faa2dc04 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -105,3 +105,6 @@ jobs:
 
       - run: mix format --check-formatted
         if: ${{ matrix.lint }}
+
+      - run: mix docs --warnings-as-errors
+        if: ${{ matrix.lint }}
diff --git a/lib/ex_doc.ex b/lib/ex_doc.ex
index f9a98a6c8..d8498345a 100644
--- a/lib/ex_doc.ex
+++ b/lib/ex_doc.ex
@@ -2,8 +2,15 @@ defmodule ExDoc do
   @moduledoc """
   Main entry point for generating docs.
   """
+
   @ex_doc_version Mix.Project.config()[:version]
 
+  @typedoc """
+  Documentation AST.
+  """
+  # Resolves to t:ExDoc.DocAST.t/0 (a public type of a hidden module)
+  @type doc_ast() :: term()
+
   @doc """
   Returns the ExDoc version (used in templates).
   """
diff --git a/lib/ex_doc/language.ex b/lib/ex_doc/language.ex
index 78c4e3000..6c884158f 100644
--- a/lib/ex_doc/language.ex
+++ b/lib/ex_doc/language.ex
@@ -78,7 +78,7 @@ defmodule ExDoc.Language do
               %{
                 id_key: binary(),
                 default_group: binary(),
-                doc_fallback: (-> ExDoc.DocAST.t()),
+                doc_fallback: (-> ExDoc.doc_ast()),
                 extra_annotations: [String.t()],
                 signature: [binary()],
                 source_file: String.t() | nil,
@@ -91,8 +91,7 @@ defmodule ExDoc.Language do
   @doc """
   Autolinks docs.
   """
-  @callback autolink_doc(doc :: ExDoc.DocAST.t(), config :: ExDoc.Autolink.t()) ::
-              ExDoc.DocAST.t()
+  @callback autolink_doc(doc :: ExDoc.doc_ast(), config :: ExDoc.Autolink.t()) :: ExDoc.doc_ast()
 
   @doc """
   Autolinks typespecs.
diff --git a/lib/ex_doc/nodes.ex b/lib/ex_doc/nodes.ex
index ba4650589..61086118e 100644
--- a/lib/ex_doc/nodes.ex
+++ b/lib/ex_doc/nodes.ex
@@ -33,7 +33,7 @@ defmodule ExDoc.ModuleNode do
           module: module(),
           group: atom() | nil,
           deprecated: String.t() | nil,
-          doc: ExDoc.DocAST.t() | nil,
+          doc: ExDoc.doc_ast() | nil,
           source_doc: term() | nil,
           source_format: String.t() | nil,
           moduledoc_line: non_neg_integer(),
@@ -81,7 +81,7 @@ defmodule ExDoc.DocNode do
           arity: non_neg_integer(),
           defaults: [function_default()],
           deprecated: String.t() | nil,
-          doc: ExDoc.DocAST.t() | nil,
+          doc: ExDoc.doc_ast() | nil,
           source_doc: term() | nil,
           type: atom(),
           signature: String.t(),
@@ -104,7 +104,7 @@ defmodule ExDoc.DocGroupNode do
   @type t :: %__MODULE__{
           title: String.t() | atom(),
           description: String.t() | nil,
-          doc: ExDoc.DocAST.t() | nil,
+          doc: ExDoc.doc_ast() | nil,
           docs: [ExDoc.DocNode.t()]
         }
 end
@@ -128,10 +128,10 @@ defmodule ExDoc.ExtraNode do
   @type t :: %__MODULE__{
           id: String.t(),
           title: String.t(),
-          title_doc: ExDoc.DocAST.t() | String.t(),
+          title_doc: ExDoc.doc_ast() | String.t(),
           group: atom() | nil,
           type: atom(),
-          doc: ExDoc.DocAST.t() | nil,
+          doc: ExDoc.doc_ast() | nil,
           source_doc: String.t(),
           source_path: String.t(),
           source_url: String.t(),