diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 4cbc4d1..663a414 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -194,7 +194,7 @@ module ApplicationHelper
   def users_select_tag(id, opts = {})
     css_class = "ajax-users-select "
     css_class << "multiselect " if opts[:multiple]
-    css_class << opts[:class] || ''
+    css_class << (opts[:class] || '')
     value = opts[:selected] || ''
 
     hidden_field_tag(id, value, class: css_class)
--
libgit2 0.21.2