diff --git a/13.ProxyPattern/2.Code/main.cpp b/13.ProxyPattern/2.Code/main.cpp
index b563585..8920ac2 100644
--- a/13.ProxyPattern/2.Code/main.cpp
+++ b/13.ProxyPattern/2.Code/main.cpp
@@ -10,7 +10,8 @@ int main()
 	printf("\n\n");
 
 	delete subject;
+	subject = nullptr;
 
 	system("pause");
 	return 0;
-}
\ No newline at end of file
+}