diff --git a/lib/enum_help/simple_form.rb b/lib/enum_help/simple_form.rb
index <HASH>..<HASH> 100644
--- a/lib/enum_help/simple_form.rb
+++ b/lib/enum_help/simple_form.rb
@@ -16,8 +16,8 @@ module EnumHelp
 
       def initialize(*args)
         super
-        raise "Attribute '#{attribute_name}' has no enum class" unless enum = object.class.send(attribute_name.to_s.pluralize)
-        return unless input_options[:collection].blank? && @builder.options[:collection].blank?
+        enum = input_options[:collection] || @builder.options[:collection]
+        raise "Attribute '#{attribute_name}' has no enum class" unless enum ||= object.class.send(attribute_name.to_s.pluralize)
 
         collect = enum.collect{|k,v| [::I18n.t("enums.#{object.class.to_s.underscore}.#{attribute_name}.#{k}", default: k),k] }
         # collect.unshift [args.last[:prompt],''] if args.last.is_a?(Hash) && args.last[:prompt]
set enum variable on collection key so that .collect gets called