diff --git a/include/string.h b/include/string.h
index 0415747..2aeeba7 100755
--- a/include/string.h
+++ b/include/string.h
@@ -14,7 +14,12 @@
 
 #include <sys/cdefs.h>
 
-#include <stddef.h>
+#include <types/size_t.h>
+#include <types/locale_t.h>
+
+#ifndef NULL
+#define NULL (void *) 0
+#endif
 
 /* Copying Functions (ISO C Std. 7.24.2) */
 void * memcpy(void * __restrict, const void * __restrict, size_t);