diff --git a/CHANGELOG b/CHANGELOG
index 066785e..889f9b0 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,5 @@
+* Further fix to ensure Object#is(String|Number) do not throw exceptions on host objects in IE. (grepmaster, kangax, Tobie Langel, Andrew Dupont)
+
 * Ensure Enumerable#grep can handle strings with RegExp metacharacters. (Marton Kiss-Albert, kangax)
 
 * Switch to the "doScroll approach" for the dom:loaded custom event. (javier, Diego Perini, Nick Stakenburg, Andrew Dupont)
diff --git a/src/lang/object.js b/src/lang/object.js
index 4d49c31..19be092 100644
--- a/src/lang/object.js
+++ b/src/lang/object.js
@@ -83,11 +83,19 @@
   }
 
   function isString(object) {
-    return typeof (object && object.valueOf()) === "string";
+    try {
+      return typeof (object && object.valueOf()) === "string";      
+    } catch(e) {
+      return false;
+    }
   }
 
   function isNumber(object) {
-    return typeof (object && object.valueOf()) === "number";
+    try {
+      return typeof (object && object.valueOf()) === "number";
+    } catch(e) {
+      return false;
+    }
   }
 
   function isUndefined(object) {
diff --git a/test/unit/object_test.js b/test/unit/object_test.js
index df340a5..37d62ab 100644
--- a/test/unit/object_test.js
+++ b/test/unit/object_test.js
@@ -135,6 +135,7 @@ new Test.Unit.Runner({
     this.assert(!Object.isString({}));
     this.assert(!Object.isString(false));
     this.assert(!Object.isString(undefined));
+    this.assert(!Object.isString(document), 'host objects should return false rather than throw exceptions');
   },
 
   testObjectIsNumber: function() {
@@ -149,6 +150,7 @@ new Test.Unit.Runner({
     this.assert(!Object.isNumber({}));
     this.assert(!Object.isNumber(false));
     this.assert(!Object.isNumber(undefined));
+    this.assert(!Object.isNumber(document), 'host objects should return false rather than throw exceptions');
   },
 
   testObjectIsUndefined: function() {