diff --git a/include/stddef.h b/include/stddef.h
new file mode 100644
index 0000000..97f72ff
--- /dev/null
+++ b/include/stddef.h
@@ -0,0 +1,19 @@
+#ifndef _STDDEF_H
+#define _STDDEF_H
+
+#ifndef _PTRDIFF_T
+#define _PTRDIFF_T
+typedef long ptrdiff_t;
+#endif
+
+#ifndef _SIZE_T
+#define _SIZE_T
+typedef unsigned long size_t;
+#endif
+
+#undef NULL
+#define NULL ((void *)0)
+
+#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
+
+#endif