diff --git a/include/msvcrt/corecrt.h b/include/msvcrt/corecrt.h
index 38acf8512eb..cff4549d376 100644
--- a/include/msvcrt/corecrt.h
+++ b/include/msvcrt/corecrt.h
@@ -41,6 +41,14 @@
 # endif
 #endif
 
+#ifndef NULL
+#ifdef __cplusplus
+#define NULL  0
+#else
+#define NULL  ((void *)0)
+#endif
+#endif
+
 #ifndef __stdcall
 # ifdef __i386__
 #  ifdef __GNUC__
diff --git a/include/msvcrt/stddef.h b/include/msvcrt/stddef.h
index 052132ed715..12025d53dc8 100644
--- a/include/msvcrt/stddef.h
+++ b/include/msvcrt/stddef.h
@@ -20,14 +20,6 @@
 
 #include <corecrt.h>
 
-#ifndef NULL
-#ifdef __cplusplus
-#define NULL  0
-#else
-#define NULL  ((void *)0)
-#endif
-#endif
-
 #ifdef __GNUC__
 #define offsetof(s,m)       __builtin_offsetof(s,m)
 #elif defined(_WIN64)
diff --git a/include/msvcrt/stdio.h b/include/msvcrt/stdio.h
index ecaa7fe611a..8a31835bea2 100644
--- a/include/msvcrt/stdio.h
+++ b/include/msvcrt/stdio.h
@@ -19,14 +19,6 @@
 #define _IOSTRG          0x0040
 #define _IORW            0x0080
 
-#ifndef NULL
-#ifdef  __cplusplus
-#define NULL  0
-#else
-#define NULL  ((void *)0)
-#endif
-#endif
-
 #define STDIN_FILENO  0
 #define STDOUT_FILENO 1
 #define STDERR_FILENO 2
diff --git a/include/msvcrt/stdlib.h b/include/msvcrt/stdlib.h
index 91fcc2a672d..78fc5fba756 100644
--- a/include/msvcrt/stdlib.h
+++ b/include/msvcrt/stdlib.h
@@ -12,14 +12,6 @@
 
 #include <pshpack8.h>
 
-#ifndef NULL
-#ifdef __cplusplus
-#define NULL  0
-#else
-#define NULL  ((void*)0)
-#endif
-#endif
-
 typedef struct
 {
     float f;
diff --git a/include/msvcrt/string.h b/include/msvcrt/string.h
index 96421cb491e..f8bc40fb2a6 100644
--- a/include/msvcrt/string.h
+++ b/include/msvcrt/string.h
@@ -15,14 +15,6 @@
 #define _NLSCMP_DEFINED
 #endif
 
-#ifndef NULL
-#ifdef __cplusplus
-#define NULL  0
-#else
-#define NULL  ((void *)0)
-#endif
-#endif
-
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/include/msvcrt/time.h b/include/msvcrt/time.h
index d55e8bbf81d..9ed27f5f9e5 100644
--- a/include/msvcrt/time.h
+++ b/include/msvcrt/time.h
@@ -29,14 +29,6 @@ typedef __msvcrt_long clock_t;
 #define _CLOCK_T_DEFINED
 #endif
 
-#ifndef NULL
-#ifdef __cplusplus
-#define NULL  0
-#else
-#define NULL  ((void *)0)
-#endif
-#endif
-
 #ifndef CLOCKS_PER_SEC
 #define CLOCKS_PER_SEC 1000
 #endif
diff --git a/include/msvcrt/wchar.h b/include/msvcrt/wchar.h
index 1fcbaa93994..119f8a2a410 100644
--- a/include/msvcrt/wchar.h
+++ b/include/msvcrt/wchar.h
@@ -17,14 +17,6 @@
 extern "C" {
 #endif
 
-#ifndef NULL
-#ifdef __cplusplus
-#define NULL  0
-#else
-#define NULL  ((void *)0)
-#endif
-#endif
-
 #ifndef WCHAR_MIN  /* also in stdint.h */
 #define WCHAR_MIN 0U
 #define WCHAR_MAX 0xffffU