diff --git a/test/index.html b/test/index.html
index 2293ebb9f..f0057617b 100644
--- a/test/index.html
+++ b/test/index.html
@@ -20,7 +20,7 @@
 		<script>
 			// set bad shims
 			Array._isArray = Array.isArray;
-			Array.isArray = function() { return false; };
+			Array.isArray = function() {};
 
 			Date._now = Date.now;
 			Date.now = function() {};
@@ -88,6 +88,7 @@
 			delete Function.prototype._bind;
 			delete Object._create;
 			delete Object._defineProperty;
+			delete Object._getPrototypeOf;
 			delete Object._keys;
 
 			QUnit.config.hidepassed = true;
diff --git a/test/test.js b/test/test.js
index 6a7ca5f4e..0c8e309cc 100644
--- a/test/test.js
+++ b/test/test.js
@@ -218,7 +218,7 @@
 
         // set bad shims
         Array._isArray = Array.isArray;
-        Array.isArray = function() { return false; };
+        Array.isArray = function() {};
 
         Date._now = Date.now;
         Date.now = function() {};
@@ -251,9 +251,11 @@
         Object.keys = Object._keys;
 
         delete Array._isArray;
+        delete Date._now;
         delete Function.prototype._bind;
         delete Object._create;
         delete Object._defineProperty;
+        delete Object._getPrototypeOf;
         delete Object._keys;
       } catch(e) { }
     }