diff --git a/app/assets/javascripts/application.js.coffee b/app/assets/javascripts/application.js.coffee
index ff0d0bb32b9..2cc8d1a00ac 100644
--- a/app/assets/javascripts/application.js.coffee
+++ b/app/assets/javascripts/application.js.coffee
@@ -63,7 +63,7 @@ window.extractLast = (term) ->
   return split( term ).pop()
 
 window.rstrip = (val) ->
-  return val.replace(/\s+$/, '')
+  return if val then val.replace(/\s+$/, '') else val
 
 # Disable button if text field is empty
 window.disableButtonIfEmptyField = (field_selector, button_selector) ->