diff --git a/can-define.js b/can-define.js
index 470c120..60a53f6 100644
--- a/can-define.js
+++ b/can-define.js
@@ -160,7 +160,8 @@ define.property = function(objPrototype, prop, definition, dataInitializers, com
 		Object.defineProperty(objPrototype, prop, {
 			get: make.get.data(prop),
 			set: make.set.events(prop, make.get.data(prop), make.set.data(prop), make.eventType.data(prop)),
-			enumerable: true
+			enumerable: true,
+			configurable: true
 		});
 		return;
 	}
@@ -243,7 +244,8 @@ define.property = function(objPrototype, prop, definition, dataInitializers, com
 	Object.defineProperty(objPrototype, prop, {
 		get: getter,
 		set: setter,
-		enumerable: "serialize" in definition ? !!definition.serialize : !definition.get
+		enumerable: "serialize" in definition ? !!definition.serialize : !definition.get,
+		configurable: true
 	});
 };
 
diff --git a/define-test.js b/define-test.js
index 872ef37..aafb685 100644
--- a/define-test.js
+++ b/define-test.js
@@ -1504,3 +1504,28 @@ QUnit.test('setter with default value causes an infinite loop (#142)', function(
 	var a = new A();
 	QUnit.equal(a.val, 'hello', 'creating an instance should not cause an inifinte loop');
 });
+
+QUnit.test('defined properties are configurable', function(){
+	var A = define.Constructor({
+		val: {
+			get: function(){
+				return "foo";
+			}
+		}
+	});
+
+	var dataInitializers = A.prototype._define.dataInitializers,
+	computedInitializers = A.prototype._define.computedInitializers;
+
+	var newDefinition = {
+		get: function(){
+			return "bar";
+		}
+	};
+
+	define.property(A.prototype, "val", newDefinition, dataInitializers,
+		computedInitializers);
+
+	var a = new A();
+	QUnit.equal(a.val, "bar", "It was redefined");
+});
diff --git a/list/list-test.js b/list/list-test.js
index 0db8bf6..913ff37 100644
--- a/list/list-test.js
+++ b/list/list-test.js
@@ -371,14 +371,12 @@ test('list.map', function() {
 		person.lastName = "Thompson";
 		return person;
 	});
-	QUnit.throws(function() {
+
+	try {
 		newExtendedList.testMe();
-	}, {
-		name: 'TypeError',
-		message: (navigator.userAgent.indexOf("Trident") > -1 ?
-			"Object doesn't support property or method 'testMe'" :
-			"newExtendedList.testMe is not a function")
-	}, 'Does not return the same type of list.');
+	} catch(err) {
+		QUnit.ok(err.message.match(/testMe/), 'Does not return the same type of list.');
+	}
 });
 
 
diff --git a/package.json b/package.json
index 81f9960..4fda1db 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "can-define",
-  "version": "1.0.21",
+  "version": "1.0.24",
   "description": "Create observable objects with JS dot operator compatibility",
   "main": "can-define.js",
   "scripts": {