diff --git a/actionpack/lib/action_view/helpers/form_helper.rb b/actionpack/lib/action_view/helpers/form_helper.rb
index 829f84dd64..4459ccbce5 100644
--- a/actionpack/lib/action_view/helpers/form_helper.rb
+++ b/actionpack/lib/action_view/helpers/form_helper.rb
@@ -471,6 +471,7 @@ module ActionView
         options = options.stringify_keys
         name_and_id = options.dup
         add_default_name_and_id(name_and_id)
+        options.delete("index")
         options["for"] ||= name_and_id["id"]
         content = (text.blank? ? nil : text.to_s) || method_name.humanize
         label_tag(name_and_id["id"], content, options)
diff --git a/actionpack/test/template/form_helper_test.rb b/actionpack/test/template/form_helper_test.rb
index 87e6ca12a1..b4857fcb62 100644
--- a/actionpack/test/template/form_helper_test.rb
+++ b/actionpack/test/template/form_helper_test.rb
@@ -540,6 +540,18 @@ class FormHelperTest < ActionView::TestCase
       _erbout
   end
 
+  def test_fields_for_object_with_bracketed_name_and_index
+    _erbout = ''
+    fields_for("author[post]", @post, :index => 1) do |f|
+      _erbout.concat f.label(:title)
+      _erbout.concat f.text_field(:title)
+    end
+
+    assert_dom_equal "<label for=\"author_post_1_title\">Title</label>" +
+      "<input name='author[post][1][title]' size='30' type='text' id='author_post_1_title' value='Hello World' />",
+      _erbout
+  end
+
   def test_form_builder_does_not_have_form_for_method
     assert ! ActionView::Helpers::FormBuilder.instance_methods.include?('form_for')
   end