diff --git a/src/manipulation.js b/src/manipulation.js
index 3b9aa1462..5f4b15dd9 100644
--- a/src/manipulation.js
+++ b/src/manipulation.js
@@ -390,8 +390,8 @@ function cloneCopyEvent(orig, ret) {
 			curData.events = {};
 
 			for ( var type in events ) {
-				for ( var handler in events[ type ] ) {
-					jQuery.event.add( this, type, events[ type ][ handler ], events[ type ][ handler ].data );
+				for ( var i = 0, l = events[ type ].length; i < l; i++ ) {
+					jQuery.event.add( this, type, events[ type ][ i ], events[ type ][ i ].data );
 				}
 			}
 		}
diff --git a/src/xhr.js b/src/xhr.js
index 57903e046..4896e6cb6 100644
--- a/src/xhr.js
+++ b/src/xhr.js
@@ -87,7 +87,7 @@ jQuery.xhr = function( _native ) {
 		}
 		
 		// Apply option prefilters
-		for (i in prefilters) {
+		for ( i = 0; i < prefilters.length; i++ ) {
 			prefilters[i](s);
 		}
 		
diff --git a/test/unit/manipulation.js b/test/unit/manipulation.js
index ba57a6f91..da1635400 100644
--- a/test/unit/manipulation.js
+++ b/test/unit/manipulation.js
@@ -1,5 +1,8 @@
 module("manipulation");
 
+// Ensure that an extended Array prototype doesn't break jQuery
+Array.prototype.arrayProtoFn = function(arg) { throw("arrayProtoFn should not be called"); };
+
 var bareObj = function(value) { return value; };
 var functionReturningObj = function(value) { return (function() { return value; }); };