diff --git a/reactos/include/crt/stdlib.h b/reactos/include/crt/stdlib.h
index cf40425ff29..2114c18e288 100644
--- a/reactos/include/crt/stdlib.h
+++ b/reactos/include/crt/stdlib.h
@@ -17,8 +17,12 @@ extern "C" {
 
 #ifndef NULL
 #ifdef __cplusplus
+#ifndef _WIN64
 #define NULL 0
 #else
+#define NULL 0LL
+#endif  /* W64 */
+#else
 #define NULL ((void *)0)
 #endif
 #endif