diff --git a/lib/ex_doc/formatter/epub.ex b/lib/ex_doc/formatter/epub.ex
index 065b37a4d..6c14b693f 100644
--- a/lib/ex_doc/formatter/epub.ex
+++ b/lib/ex_doc/formatter/epub.ex
@@ -87,6 +87,11 @@ defmodule ExDoc.Formatter.EPUB do
   end
 
   defp generate_nav(config, nodes) do
+    nodes =
+      Map.update!(nodes, :modules, fn modules ->
+        modules |> Enum.chunk_by(& &1.group) |> Enum.map(&{hd(&1).group, &1})
+      end)
+
     content = Templates.nav_template(config, nodes)
     File.write("#{config.output}/OEBPS/nav.xhtml", content)
   end
diff --git a/lib/ex_doc/formatter/epub/templates.ex b/lib/ex_doc/formatter/epub/templates.ex
index 57f10dcb2..5762de792 100644
--- a/lib/ex_doc/formatter/epub/templates.ex
+++ b/lib/ex_doc/formatter/epub/templates.ex
@@ -109,6 +109,14 @@ defmodule ExDoc.Formatter.EPUB.Templates do
     trim: true
   )
 
+  EEx.function_from_file(
+    :defp,
+    :nav_grouped_item_template,
+    Path.expand("templates/nav_grouped_item_template.eex", __DIR__),
+    [:nodes],
+    trim: true
+  )
+
   EEx.function_from_file(
     :defp,
     :toc_item_template,
diff --git a/lib/ex_doc/formatter/epub/templates/nav_grouped_item_template.eex b/lib/ex_doc/formatter/epub/templates/nav_grouped_item_template.eex
new file mode 100644
index 000000000..67b1d0396
--- /dev/null
+++ b/lib/ex_doc/formatter/epub/templates/nav_grouped_item_template.eex
@@ -0,0 +1,13 @@
+<%= for {title, nodes} <- nodes do %>
+  <%= if title do %>
+    <li><span><%=h to_string(title) %></span>
+      <ol>
+  <% end %>
+  <%= for node <- nodes do %>
+      <li><a href="<%= URI.encode node.id %>.xhtml"><%=h node.title %></a></li>
+  <% end %>
+  <%= if title do %>
+      </ol>
+    </li>
+  <% end %>
+<% end %>
diff --git a/lib/ex_doc/formatter/epub/templates/nav_template.eex b/lib/ex_doc/formatter/epub/templates/nav_template.eex
index 88af07185..52cb08e6c 100644
--- a/lib/ex_doc/formatter/epub/templates/nav_template.eex
+++ b/lib/ex_doc/formatter/epub/templates/nav_template.eex
@@ -2,21 +2,17 @@
     <h1>Table of contents</h1>
     <nav epub:type="toc">
       <ol>
-        <%= for {title, extras} <- config.extras do %>
-          <%= if title do %>
-            <li><span><%=h to_string(title) %></span>
-              <ol>
-          <% end %>
-          <%= for extra <- extras do %>
-              <li><a href="<%= URI.encode extra.id %>.xhtml"><%=h extra.title %></a></li>
-          <% end %>
-          <%= if title do %>
-              </ol>
-            </li>
-          <% end %>
-        <% end %>
+        <%= nav_grouped_item_template config.extras  %>
 
-        <%= nav_item_template "Modules", nodes.modules %>
+        <%= unless Enum.empty?(nodes.modules) do %>
+        <ol>
+          <li><span>Modules</span>
+            <ol>
+            <%= nav_grouped_item_template nodes.modules  %>
+            </ol>
+          </li>
+        </ol>
+        <% end %>
         <%= nav_item_template "Mix Tasks", nodes.tasks %>
       </ol>
     </nav>
diff --git a/test/ex_doc/formatter/html_test.exs b/test/ex_doc/formatter/html_test.exs
index 5bee818b7..1c883cf98 100644
--- a/test/ex_doc/formatter/html_test.exs
+++ b/test/ex_doc/formatter/html_test.exs
@@ -131,7 +131,7 @@ defmodule ExDoc.Formatter.HTMLTest do
         generate_docs(doc_config(context, skip_undefined_reference_warnings_on: []))
       end)
 
-    assert out =~ ~s| documentation references function \"Warnings.bar/0\" but|
+    assert out =~ ~s|documentation references function "Warnings.bar/0" but|
 
     # TODO: remove check when we require Elixir v1.16
     if Version.match?(System.version(), ">= 1.16.0-rc") do