diff --git a/CHANGELOG b/CHANGELOG
index c3fd9ee..bac2d0c 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,5 @@
+* Make Ajax.Updater clone its options hash before modifying it. Prevents memory leaks in Ajax.PeriodicalUpdater. Closes #10049 [Mislav Marohnić, Tobie Langel].
+
 * Remove useless variable in Selector.handlers.child. Closes #10006 [kuriyama]
 
 * Don't redeclare previously declared variables. Closes #10007 [kuriyama]
diff --git a/src/ajax.js b/src/ajax.js
index d7790b0..0ecec59 100644
--- a/src/ajax.js
+++ b/src/ajax.js
@@ -306,11 +306,11 @@ Ajax.Updater = Class.create(Ajax.Request, {
       failure: (container.failure || (container.success ? null : container))
     };
 
-    options = options || { };
+    options = Object.clone(options);
     var onComplete = options.onComplete;
-    options.onComplete = (function(response, param) {
+    options.onComplete = (function(response, json) {
       this.updateContent(response.responseText);
-      if (Object.isFunction(onComplete)) onComplete(response, param);
+      if (Object.isFunction(onComplete)) onComplete(response, json);
     }).bind(this);
 
     $super(url, options);
@@ -332,10 +332,6 @@ Ajax.Updater = Class.create(Ajax.Request, {
       } 
       else receiver.update(responseText);
     }
-    
-    if (this.success()) {
-      if (this.onComplete) this.onComplete.bind(this).defer();
-    }
   }
 });
 
diff --git a/test/unit/ajax.html b/test/unit/ajax.html
index 7e7e98e..0de88a0 100644
--- a/test/unit/ajax.html
+++ b/test/unit/ajax.html
@@ -161,7 +161,19 @@
         });
       });
     }},
-       
+    
+    testUpdaterOptions: function() {with(this) {
+      var options = {
+        method: 'get',
+        asynchronous: false,
+        evalJS: 'force',
+        onComplete: Prototype.emptyFunction
+      }
+      var request = new Ajax.Updater("content", "fixtures/hello.js", options);
+      request.options.onComplete = function() {};
+      assertIdentical(Prototype.emptyFunction, options.onComplete);
+    }},
+    
     testResponders: function(){with(this) {
       // check for internal responder
       assertEqual(1, Ajax.Responders.responders.length);