diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 112e86a4f..8abd400d8 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -21,7 +21,8 @@ class ApplicationController < ActionController::Base
   protected
 
   def set_locale
-    I18n.locale = check_locale( get_user_locale || request.env['HTTP_ACCEPT_LANGUAGE'][0,2].downcase )
+    I18n.locale = check_locale( get_user_locale ||
+      request.env['HTTP_ACCEPT_LANGUAGE'] ? request.env['HTTP_ACCEPT_LANGUAGE'][0,2].downcase : nil )
   end
 
   def get_user_locale