diff --git a/lib/sidekiq/web_helpers.rb b/lib/sidekiq/web_helpers.rb
index 42f327f3..d21be901 100644
--- a/lib/sidekiq/web_helpers.rb
+++ b/lib/sidekiq/web_helpers.rb
@@ -21,7 +21,7 @@ module Sidekiq
     end
 
     def locale
-      lang = (request.env["HTTP_ACCEPT_LANGUAGE"] || 'en')[0,2]
+      lang = (request.env["HTTP_ACCEPT_LANGUAGE"] || 'en').split(',')[0].downcase
       strings[lang] ? lang : 'en'
     end