diff --git a/activerecord/test/cases/xml_serialization_test.rb b/activerecord/test/cases/xml_serialization_test.rb
index e1ad5c16851a6..2849ff11b7a26 100644
--- a/activerecord/test/cases/xml_serialization_test.rb
+++ b/activerecord/test/cases/xml_serialization_test.rb
@@ -130,10 +130,20 @@ def test_should_serialize_yaml
 end
 
 class DatabaseConnectedXmlSerializationTest < ActiveRecord::TestCase
-  fixtures :authors, :posts
+  fixtures :authors, :posts, :projects
+
   # to_xml used to mess with the hash the user provided which
   # caused the builder to be reused.  This meant the document kept
   # getting appended to.
+
+  def test_modules
+    projects = MyApplication::Business::Project.all
+    xml = projects.to_xml
+    root = projects.first.class.to_s.underscore.pluralize.tr('/','_').dasherize
+    assert_match "<#{root} type=\"array\">", xml
+    assert_match "</#{root}>", xml
+  end
+
   def test_passing_hash_shouldnt_reuse_builder
     options = {:include=>:posts}
     david = authors(:david)
diff --git a/activesupport/lib/active_support/core_ext/array/conversions.rb b/activesupport/lib/active_support/core_ext/array/conversions.rb
index 2119322bfe5c1..5d8e78e6e5c7e 100644
--- a/activesupport/lib/active_support/core_ext/array/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/array/conversions.rb
@@ -131,7 +131,7 @@ def to_xml(options = {})
     require 'builder' unless defined?(Builder)
 
     options = options.dup
-    options[:root]     ||= all? { |e| e.is_a?(first.class) && first.class.to_s != "Hash" } ? ActiveSupport::Inflector.pluralize(ActiveSupport::Inflector.underscore(first.class.name)) : "records"
+    options[:root]     ||= all? { |e| e.is_a?(first.class) && first.class.to_s != "Hash" } ? ActiveSupport::Inflector.pluralize(ActiveSupport::Inflector.underscore(first.class.name)).tr('/', '_') : "records"
     options[:children] ||= options[:root].singularize
     options[:indent]   ||= 2
     options[:builder]  ||= Builder::XmlMarkup.new(:indent => options[:indent])