diff --git a/object.js b/object.js
index 7e7dfb7..8d766d3 100644
--- a/object.js
+++ b/object.js
@@ -120,16 +120,22 @@ define(function (require) {
 		'object-isextensible': 'isExtensible',
 		'object-preventextensions': 'preventExtensions',
 		'object-defineproperty-obj': function () {
-			return hasDefineProperty({});
+			return hasDefineProperty({}, 'sentinel1', { value: true });
 		},
 		'object-defineproperty-dom': function () {
-			return doc && hasDefineProperty(testEl);
+			return doc && hasDefineProperty(testEl, 'sentinel1', { value: true });
+		},
+		'object-defineproperty-function': function () {
+			return hasDefineProperty(function () {}, 'prototype', { value: { test: true } });
 		},
 		'object-defineproperties-obj': function () {
-			return hasDefineProperties({});
+			return hasDefineProperties({}, { 'sentinel2': { value: true } });
 		},
 		'object-defineproperties-dom': function () {
-			return doc && hasDefineProperties(testEl);
+			return doc && hasDefineProperties(testEl, { 'sentinel2': { value: true } });
+		},
+		'object-defineproperties-function': function () {
+			return hasDefineProperties(function () {}, { 'prototype': { value: { test: true } } });
 		},
 		'object-getownpropertydescriptor-obj': function () {
 			return hasGetOwnPropertyDescriptor({});
@@ -189,7 +195,7 @@ define(function (require) {
 			= getOwnPropertyNames;
 	}
 
-	if (!has('object-defineproperties-obj')) {
+	if (!has('object-defineproperties-obj') || !has('object-defineproperties-function')) {
 		// check if dom has it (IE8)
 		Object.defineProperties = shims.defineProperties
 			= has('object-defineproperties-dom')
@@ -197,7 +203,7 @@ define(function (require) {
 				: defineProperties;
 	}
 
-	if (!has('object-defineproperty-obj')) {
+	if (!has('object-defineproperty-obj') || !has('object-defineproperty-function')) {
 		// check if dom has it (IE8)
 		Object.defineProperty = shims.defineProperty
 			= has('object-defineproperty-dom')
@@ -221,12 +227,12 @@ define(function (require) {
 				: getOwnPropertyDescriptor;
 	}
 
-	function hasDefineProperty (object) {
+	function hasDefineProperty (object, prop, descriptor) {
 		if (('defineProperty' in Object)) {
 			try {
 				// test it
-				Object.defineProperty(object, 'sentinel1', { value: true })
-				return object['sentinel1'] === true;
+				Object.defineProperty(object, prop, descriptor)
+				return object[prop] === descriptor.value;
 			}
 			catch (ex) { /* squelch */ }
 		}
@@ -234,12 +240,21 @@ define(function (require) {
 
 	// Note: MSDN docs say that IE8 has this function, but tests show
 	// that it does not! JMH
-	function hasDefineProperties (object) {
+	function hasDefineProperties (object, props) {
+		var keys, property;
+
 		if (('defineProperties' in Object)) {
 			try {
 				// test it
-				Object.defineProperties(object, { 'sentinel2': { value: true } })
-				return object['sentinel2'] === true;
+				Object.defineProperties(object, props);
+				keys = _keys(props);
+
+				while (property = keys.pop()) {
+					if (object[property] !== props[property].value) {
+						return false;
+					}
+				}
+				return true;
 			}
 			catch (ex) { /* squelch */ }
 		}
diff --git a/test/object.html b/test/object.html
index 4fcbb6f..8d3dbef 100644
--- a/test/object.html
+++ b/test/object.html
@@ -258,6 +258,13 @@
 			Object.defineProperty(test, 'foo', { value: 5 });
 			return test.foo == 5;
 		});
+		tester.assertTrue("Object.defineProperty should define the prototype property correctly", function () {
+			function fn() {};
+
+			Object.defineProperty(fn, 'prototype', { value: { test: true } });
+
+			return fn.prototype.test === true && (new fn).test === true;
+		});
 		tester.assertTrue('Object.defineProperties should add several properties', function () {
 			var test = {};
 			// writable and get don't actually work, just putting them in here