1 files changed, 8 insertions, 4 deletions
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index d91e4a2b6a..f90030641d 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -300,13 +300,17 @@ module ActiveModel
     def generate_message(attribute, type = :invalid, options = {})
       type = options.delete(:message) if options[:message].is_a?(Symbol)
 
-      defaults = @base.class.lookup_ancestors.map do |klass|
-        [ :"#{@base.class.i18n_scope}.errors.models.#{klass.model_name.i18n_key}.attributes.#{attribute}.#{type}",
-          :"#{@base.class.i18n_scope}.errors.models.#{klass.model_name.i18n_key}.#{type}" ]
+      if @base.class.respond_to?(:i18n_scope)
+        defaults = @base.class.lookup_ancestors.map do |klass|
+          [ :"#{@base.class.i18n_scope}.errors.models.#{klass.model_name.i18n_key}.attributes.#{attribute}.#{type}",
+            :"#{@base.class.i18n_scope}.errors.models.#{klass.model_name.i18n_key}.#{type}" ]
+        end
+      else
+        defaults = []
       end
 
       defaults << options.delete(:message)
-      defaults << :"#{@base.class.i18n_scope}.errors.messages.#{type}"
+      defaults << :"#{@base.class.i18n_scope}.errors.messages.#{type}" if @base.class.respond_to?(:i18n_scope)
       defaults << :"errors.attributes.#{attribute}.#{type}"
       defaults << :"errors.messages.#{type}"