diff --git a/turbob64.h b/turbob64.h
index 0149b77..2ddd838 100644
--- a/turbob64.h
+++ b/turbob64.h
@@ -24,6 +24,9 @@
// Turbo-Base64 - C/C++ include header
#ifndef _TURBOB64_H_
#define _TURBOB64_H_
+
+#include <stddef.h>
#ifdef __cplusplus
extern "C" {
#endif
