diff --git a/CHANGES.rst b/CHANGES.rst
index 86bcb2c..295f1d4 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -8,6 +8,9 @@ Changelog
   there are no replies yet.
   [gaudenz]
 
+- Don't execute createReplyForm js if there is no in_reply_to button.
+  [vincentfretin]
+
 - Register events as Content Rules Event Types if plone.contentrules is present
   [avoinea]
 
diff --git a/plone/app/discussion/browser/javascripts/comments.js b/plone/app/discussion/browser/javascripts/comments.js
index 3060a3d..7b492c7 100644
--- a/plone/app/discussion/browser/javascripts/comments.js
+++ b/plone/app/discussion/browser/javascripts/comments.js
@@ -106,7 +106,7 @@
         var post_comment_div = $("#commenting");
         var in_reply_to_field =
             post_comment_div.find("input[name='form.widgets.in_reply_to']");
-        if (in_reply_to_field.val() !== "") {
+        if (in_reply_to_field.length !== 0 && in_reply_to_field.val() !== "") {
             var current_reply_id = "#" + in_reply_to_field.val();
             var current_reply_to_div = $(".discussion").find(current_reply_id);
             $.createReplyForm(current_reply_to_div);