diff --git a/README.md b/README.md
index d3be105..f7eefc0 100644
--- a/README.md
+++ b/README.md
@@ -114,6 +114,7 @@ V::lang('ar');
  * `dateAfter` - Field is a valid date and is after the given date
  * `contains` - Field is a string and contains the given string
  * `creditCard` - Field is a valid credit card number
+ * `instanceOf` - Field contains an instance of the given class
 
 **NOTE**: If you are comparing floating-point numbers with min/max validators, you
 should install the [BCMath](http://us3.php.net/manual/en/book.bc.php)
diff --git a/lang/en.php b/lang/en.php
index d768a20..f20c85e 100644
--- a/lang/en.php
+++ b/lang/en.php
@@ -29,5 +29,6 @@ return array(
     'lengthBetween' => "must be between %d and %d characters",
     'creditCard'    => "must be a valid credit card number",
     "lengthMin"     => "must contain greater than %d characters",
-    "lengthMax"     => "must contain less than %d characters"
+    "lengthMax"     => "must contain less than %d characters",
+    "instanceOf"    => "must be an instance of '%s'"
 );
diff --git a/src/Valitron/Validator.php b/src/Valitron/Validator.php
index 15bb32c..b9b4e41 100644
--- a/src/Valitron/Validator.php
+++ b/src/Valitron/Validator.php
@@ -736,6 +736,10 @@ class Validator
             }
             if ($param instanceof \DateTime) {
                 $param = $param->format('Y-m-d');
+            } else {
+                if(is_object($param)) {
+                    $param = get_class($param);
+                }
             }
             // Use custom label instead of field name if set
             if(is_string($params[0])) {
diff --git a/tests/Valitron/ValidateTest.php b/tests/Valitron/ValidateTest.php
index eb51756..acd566e 100644
--- a/tests/Valitron/ValidateTest.php
+++ b/tests/Valitron/ValidateTest.php
@@ -833,6 +833,19 @@ class ValidateTest extends BaseTestCase
       $this->assertTrue($v->validate());
     }
 
+    public function testInstanceOfErrorMessageShowsInstanceName()
+    {
+      $v = new Validator(array('attributeName' => new Validator(array())));
+      $v->rule('instanceOf', 'attributeName', new stdClass());
+      $v->validate();
+      $expected_error = array(
+        "attributeName" => array(
+          "AttributeName must be an instance of 'stdClass'"
+        )
+      );
+      $this->assertEquals($expected_error, $v->errors());
+    }
+
     public function testInstanceOfInvalidWithString()
     {
       $v = new Validator(array('attributeName' => new stdClass()));