diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index a8d8e330..0bea70c3 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -15,7 +15,7 @@ def set_locale
 
     locale = params[:locale] || locale_from_header
 
-    if SYS::LOCALES_MAP.values.include?(locale.to_sym)
+    if !locale.nil? && SYS::LOCALES_MAP.values.include?(locale.to_sym)
       I18n.locale = locale
     else
       I18n.locale = I18n.default_locale