diff --git a/CHANGELOG b/CHANGELOG
index 8833204..de207b3 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Fix Ajax.PeriodicalUpdater for compatibility with Ajax.Response.  Closes #9321.  [kampers]
+
 * Ensure that classes always have an initialize method.  [Mislav Marohnić]
 
 * Update Template, Selector, Ajax.*, and ObjectRange classes to use the new class system.  [Mislav Marohnić]
diff --git a/src/ajax.js b/src/ajax.js
index e2a8998..9a63358 100644
--- a/src/ajax.js
+++ b/src/ajax.js
@@ -362,12 +362,12 @@ Ajax.PeriodicalUpdater = Class.create(Ajax.Base, {
     (this.onComplete || Prototype.emptyFunction).apply(this, arguments);
   },
 
-  updateComplete: function(responseText) {
+  updateComplete: function(response) {
     if (this.options.decay) {
-      this.decay = (responseText == this.lastText ? 
+      this.decay = (response.responseText == this.lastText ? 
         this.decay * this.options.decay : 1);
 
-      this.lastText = responseText;
+      this.lastText = response.responseText;
     }
     this.timer = this.onTimerEvent.bind(this).delay(this.decay * this.frequency);
   },