diff --git a/core/lib/crc16.c b/core/lib/crc16.c
index 9be8317f9..4508426b0 100644
--- a/core/lib/crc16.c
+++ b/core/lib/crc16.c
@@ -28,7 +28,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * @(#)$Id: crc16.c,v 1.2 2008/07/07 23:24:36 adamdunkels Exp $
+ * @(#)$Id: crc16.c,v 1.3 2008/08/26 21:46:06 adamdunkels Exp $
  */
 
 /** \addtogroup crc16
@@ -64,7 +64,7 @@ crc16_add(unsigned char b, unsigned short acc)
 }
 /*---------------------------------------------------------------------------*/
 unsigned short
-crc16_data(unsigned char *data, int len, unsigned short acc)
+crc16_data(const unsigned char *data, int len, unsigned short acc)
 {
   int i;
   unsigned short crc = 0;
diff --git a/core/lib/crc16.h b/core/lib/crc16.h
index 827bf6d8c..2cea147b4 100644
--- a/core/lib/crc16.h
+++ b/core/lib/crc16.h
@@ -50,7 +50,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * @(#)$Id: crc16.h,v 1.2 2008/07/07 23:24:36 adamdunkels Exp $
+ * @(#)$Id: crc16.h,v 1.3 2008/08/26 21:46:07 adamdunkels Exp $
  */
 #ifndef __CRC16_H__
 #define __CRC16_H__
@@ -87,7 +87,7 @@ unsigned short crc16_add(unsigned char b, unsigned short crc);
  *             well as a table-driven algorithm when checksumming an
  *             entire data block.
  */
-unsigned short crc16_data(unsigned char *data, int datalen,
+unsigned short crc16_data(const unsigned char *data, int datalen,
 			  unsigned short acc);
 
 #endif /* __CRC16_H__ */