diff --git a/app/helpers/watchers_helper.rb b/app/helpers/watchers_helper.rb
index be5609d7c..b05e0b286 100644
--- a/app/helpers/watchers_helper.rb
+++ b/app/helpers/watchers_helper.rb
@@ -211,13 +211,17 @@ module WatchersHelper
   end
 
   def watchers_checkboxes(object, users, checked=nil)
-    users.map do |user|
-      c = checked.nil? ? object.watched_by?(user) : checked
-      tag = check_box_tag 'issue[watcher_user_ids][]', user.id, c, :id => nil
-      content_tag 'label', "#{tag} #{h(user)}".html_safe,
-                  :id => "issue_watcher_user_ids_#{user.id}",
-                  :class => "floating"
-    end.join.html_safe
+    if users.nil?
+
+    else
+      users.map do |user|
+        c = checked.nil? ? object.watched_by?(user) : checked
+        tag = check_box_tag 'issue[watcher_user_ids][]', user.id, c, :id => nil
+        content_tag 'label', "#{tag} #{h(user)}".html_safe,
+                    :id => "issue_watcher_user_ids_#{user.id}",
+                    :class => "floating"
+      end.join.html_safe
+    end
   end
 
   def applied_css(project)