diff --git a/skyquake/plugins/logging/api/transforms.js b/skyquake/plugins/logging/api/transforms.js
index 5f65010..f4bfda6 100644
--- a/skyquake/plugins/logging/api/transforms.js
+++ b/skyquake/plugins/logging/api/transforms.js
@@ -168,7 +168,7 @@
  * or absence of the { "allow": { "duplicate": "events" }} key/value hierarchy
  */
 LoggingConfigEncoder.prototype.allow = function(data) {
-  if (data.allowDuplicateEvents.toUpperCase() == "TRUE") {
+  if (data.allowDuplicateEvent && data.allowDuplicateEvents.toUpperCase() == "TRUE") {
     return { duplicate: "events" };
   } else {
     return null;