diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index 889c80386f..3e27e85f02 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -244,7 +244,7 @@ def arel_attributes_values(include_primary_key = true, include_readonly_attribut
     end
 
     def attribute_method?(attr_name)
-      attr_name == 'id' || (defined?(@attributes) && @attributes.include?(attr_name))
+      defined?(@attributes) && @attributes.include?(attr_name)
     end
   end
 end
diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index 7c59664703..2e1a2dc3ef 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -24,6 +24,12 @@ def id?
         query_attribute(self.class.primary_key)
       end
 
+      protected
+
+      def attribute_method?(attr_name)
+        attr_name == 'id' || super
+      end
+
       module ClassMethods
         def define_method_attribute(attr_name)
           super