If default is provided don't add attribute.to_s.humanize to the options

activemodel/lib/active_model/translation.rb

@@ -48,8 +48,7 @@ def human_attribute_name(attribute, options = {})
       end
 
       defaults << :"attributes.#{attribute}"
-      defaults << options.delete(:default) if options[:default]
-      defaults << attribute.to_s.humanize
+      defaults << (options[:default] ? options.delete(:default) : attribute.to_s.humanize)
 
       options.reverse_merge! :count => 1, :default => defaults
       I18n.translate(defaults.shift, options)