diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 2d9d339a4c..b83fe7b3f6 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -1033,9 +1033,9 @@ module ApplicationHelper
   def javascript_heads
     tags = javascript_include_tag(:defaults)
     unless User.current.pref.warn_on_leaving_unsaved == '0'
-      tags << "\n" + javascript_tag("Event.observe(window, 'load', function(){ new WarnLeavingUnsaved('#{escape_javascript( l(:text_warn_on_leaving_unsaved) )}'); });")
+      tags.safe_concat "\n" + javascript_tag("Event.observe(window, 'load', function(){ new WarnLeavingUnsaved('#{escape_javascript( l(:text_warn_on_leaving_unsaved) )}'); });")
     end
-    tags << "\n" + javascript_include_tag("accessibility.js") if User.current.impaired? and accessibility_js_enabled?
+    tags.safe_concat("\n" + javascript_include_tag("accessibility.js")) if User.current.impaired? and accessibility_js_enabled?
     tags
   end