diff --git a/src/csn1.h b/src/csn1.h
index a50b6cd..2d84f7e 100644
--- a/src/csn1.h
+++ b/src/csn1.h
@@ -82,7 +82,7 @@
   gint  direction;           /* 0 - decode; 1 - encode */
 } csnStream_t;
 
-typedef gint16 (*StreamSerializeFcn_t)(csnStream_t* ar, bitvec *vector, size_t& readIndex, void* data);
+typedef gint16 (*StreamSerializeFcn_t)(csnStream_t* ar, bitvec *vector, unsigned& readIndex, void* data);
 typedef enum
 {
   CSN_END = 0,
@@ -187,7 +187,7 @@
     void*     ptr;
     guint32   value;
   } descr;
-  size_t      offset;
+  unsigned      offset;
   const char* sz;
   union
   {
@@ -223,9 +223,9 @@
 * RETURNS:  int  Number of bits left to be unpacked. Negative Error code if failed to unpack all bits
 ******************************************************************************/
 
-gint16 csnStreamDecoder(csnStream_t* ar, const CSN_DESCR* pDescr, bitvec *vector, size_t& readIndex, void* data);
+gint16 csnStreamDecoder(csnStream_t* ar, const CSN_DESCR* pDescr, bitvec *vector, unsigned& readIndex, void* data);
 
-gint16 csnStreamEncoder(csnStream_t* ar, const CSN_DESCR* pDescr, bitvec *vector, size_t& readIndex, void* data);
+gint16 csnStreamEncoder(csnStream_t* ar, const CSN_DESCR* pDescr, bitvec *vector, unsigned& readIndex, void* data);
 
 /* CSN struct macro's */
 #define  CSN_DESCR_BEGIN(_STRUCT)\