diff --git a/cocos/2d/CCUserDefault.cpp b/cocos/2d/CCUserDefault.cpp
index 1a83091dfe..d81596fca6 100644
--- a/cocos/2d/CCUserDefault.cpp
+++ b/cocos/2d/CCUserDefault.cpp
@@ -479,7 +479,7 @@ bool UserDefault::createXMLFile()
     {  
         return false;  
     }  
-	tinyxml2::XMLDeclaration *pDeclaration = pDoc->NewDeclaration(NULL);  
+	tinyxml2::XMLDeclaration *pDeclaration = pDoc->NewDeclaration(nullptr);  
 	if (NULL==pDeclaration)  
 	{  
 		return false;