diff --git a/app/controllers/protocols_controller.rb b/app/controllers/protocols_controller.rb
index 9116cb4d4..4b944f316 100644
--- a/app/controllers/protocols_controller.rb
+++ b/app/controllers/protocols_controller.rb
@@ -180,8 +180,10 @@ class ProtocolsController < ApplicationController
   def update_keywords
     respond_to do |format|
       # sanitize user input
-      params[:keywords].collect! do |keyword|
-        escape_input(keyword)
+      if params[:keywords]
+        params[:keywords].collect! do |keyword|
+          escape_input(keyword)
+        end
       end
       if @protocol.update_keywords(params[:keywords])
         format.json do