diff --git a/include/alloca.h b/include/alloca.h
index 692f8fb0..aceea860 100644
--- a/include/alloca.h
+++ b/include/alloca.h
@@ -29,11 +29,7 @@
 
 #else // ! SYSTEM_LIBC
 
-#ifndef __MES_SIZE_T
-#define __MES_SIZE_T
-#undef size_t
-typedef unsigned long size_t;
-#endif
+#include <sys/types.h>
 
 #if _ALLOCA_UNSIGNED
 void *alloca (unsigned size);
diff --git a/include/stdint.h b/include/stdint.h
index 68821dbe..8b8994e3 100644
--- a/include/stdint.h
+++ b/include/stdint.h
@@ -58,28 +58,10 @@ typedef int int32_t;
 typedef unsigned long long uint64_t;
 typedef long long int64_t;
 
-#ifndef __MES_SIZE_T
-#define __MES_SIZE_T
-#undef size_t
-typedef unsigned long size_t;
-#endif
-
-#ifndef __MES_INTPTR_T
-#define __MES_INTPTR_T
-#undef intptr_t
-typedef long intptr_t;
-#endif
-
-// FIXME
 typedef int intmax_t;
 typedef unsigned uintmax_t;
-typedef unsigned* uintptr_t;
 
-#ifndef __MES_PTRDIFF_T
-#define __MES_PTRDIFF_T
-#undef ptrdiff_t
-typedef long ptrdiff_t;
-#endif
+#include <sys/types.h>
 
 #define CHAR_BIT 8
 #define CHAR_MAX 255
diff --git a/include/string.h b/include/string.h
index e8748dd6..60b2887e 100644
--- a/include/string.h
+++ b/include/string.h
@@ -29,21 +29,7 @@
 
 #else // ! SYSTEM_LIBC
 
-#ifndef NULL
-#define NULL 0
-#endif
-
-#ifndef __MES_SIZE_T
-#define __MES_SIZE_T
-#undef size_t
-typedef unsigned long size_t;
-#endif
-
-#ifndef __MES_SSIZE_T
-#define __MES_SSIZE_T
-#undef ssize_t
-typedef long ssize_t;
-#endif
+#include <sys/types.h>
 
 void *memchr (void const *block, int c, size_t size);
 void *memcpy (void *dest, void const *src, size_t n);