diff --git a/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php b/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
index 01d5b77dd..73b555666 100644
--- a/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
+++ b/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
@@ -866,7 +866,11 @@ class ClassMetadataInfo implements ClassMetadata
     public function newInstance()
     {
         if ($this->_prototype === null) {
-            $this->_prototype = unserialize(sprintf('O:%d:"%s":0:{}', strlen($this->name), $this->name));
+            if (PHP_VERSION_ID === 50428 || PHP_VERSION_ID === 50513) {
+                $this->_prototype = $this->reflClass->newInstanceWithoutConstructor();
+            } else {
+                $this->_prototype = unserialize(sprintf('O:%d:"%s":0:{}', strlen($this->name), $this->name));
+            }
         }
 
         return clone $this->_prototype;