3 files changed, 8 insertions, 3 deletions
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index 00bd68512b..7eaee050cd 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -84,7 +84,7 @@ module ActiveModel
     end
 
     # Backport dup from 1.9 so that #initialize_dup gets called
-    unless Object.respond_to?(:initialize_dup)
+    unless Object.respond_to?(:initialize_dup, true)
       def dup # :nodoc:
         copy = super
         copy.initialize_dup(self)
diff --git a/activemodel/lib/active_model/serializers/xml.rb b/activemodel/lib/active_model/serializers/xml.rb
index 2dc7d00f52..a63856045f 100644
--- a/activemodel/lib/active_model/serializers/xml.rb
+++ b/activemodel/lib/active_model/serializers/xml.rb
@@ -144,7 +144,12 @@ module ActiveModel
             end
           else
             merged_options[:root] = association.to_s
-            records.to_xml(merged_options)
+
+            unless records.class.to_s.underscore == association.to_s
+              merged_options[:type] = records.class.name
+            end
+
+            records.to_xml merged_options
           end
         end
 
diff --git a/activemodel/lib/active_model/validations.rb b/activemodel/lib/active_model/validations.rb
index 45d8677fa0..c7e508958b 100644
--- a/activemodel/lib/active_model/validations.rb
+++ b/activemodel/lib/active_model/validations.rb
@@ -173,7 +173,7 @@ module ActiveModel
     end
 
     # Backport dup from 1.9 so that #initialize_dup gets called
-    unless Object.respond_to?(:initialize_dup)
+    unless Object.respond_to?(:initialize_dup, true)
       def dup # :nodoc:
         copy = super
         copy.initialize_dup(self)