diff --git a/src/DeepCopy/DeepCopy.php b/src/DeepCopy/DeepCopy.php
index 15e5c68..b1b4e3f 100644
--- a/src/DeepCopy/DeepCopy.php
+++ b/src/DeepCopy/DeepCopy.php
@@ -194,6 +194,7 @@ private function copyObject($object)
         }
 
         $newObject = clone $object;
+        $objectHash = spl_object_hash($newObject);
         $this->hashMap[$objectHash] = $newObject;
 
         if ($this->useCloneMethod && $reflectedObject->hasMethod('__clone')) {