diff --git a/PHPUnit/Framework/Constraint/IsInstanceOf.php b/PHPUnit/Framework/Constraint/IsInstanceOf.php
index cb5491e09f8..a9e2e3b3003 100644
--- a/PHPUnit/Framework/Constraint/IsInstanceOf.php
+++ b/PHPUnit/Framework/Constraint/IsInstanceOf.php
@@ -103,8 +103,9 @@ public function fail($other, $description, $not = FALSE)
     {
         throw new PHPUnit_Framework_ExpectationFailedException(
           sprintf(
-            'Failed asserting that %s is %san instance of class "%s".',
+            '%sFailed asserting that %s is %san instance of class "%s".',
 
+            !empty($description) ? $description . "\n" : '',
             PHPUnit_Util_Type::toString($other, TRUE),
             $not ? 'not ' : '',
             $this->className