diff --git a/library/sha2.c b/library/sha2.c
index dd5ae98..64ebc43 100644
--- a/library/sha2.c
+++ b/library/sha2.c
@@ -34,7 +34,6 @@
 
 #include "polarssl/sha2.h"
 
-#include <string.h>
 #include <stdio.h>
 
 /*
@@ -230,9 +229,9 @@
 /*
  * SHA-256 process buffer
  */
-void sha2_update( sha2_context *ctx, const unsigned char *input, int ilen )
+void sha2_update( sha2_context *ctx, const unsigned char *input, size_t ilen )
 {
-    int fill;
+    size_t fill;
     unsigned long left;
 
     if( ilen <= 0 )
@@ -241,7 +240,7 @@
     left = ctx->total[0] & 0x3F;
     fill = 64 - left;
 
-    ctx->total[0] += ilen;
+    ctx->total[0] += (unsigned long) ilen;
     ctx->total[0] &= 0xFFFFFFFF;
 
     if( ctx->total[0] < (unsigned long) ilen )
@@ -316,7 +315,7 @@
 /*
  * output = SHA-256( input buffer )
  */
-void sha2( const unsigned char *input, int ilen,
+void sha2( const unsigned char *input, size_t ilen,
            unsigned char output[32], int is224 )
 {
     sha2_context ctx;
@@ -363,10 +362,10 @@
 /*
  * SHA-256 HMAC context setup
  */
-void sha2_hmac_starts( sha2_context *ctx, const unsigned char *key, int keylen,
+void sha2_hmac_starts( sha2_context *ctx, const unsigned char *key, size_t keylen,
                        int is224 )
 {
-    int i;
+    size_t i;
     unsigned char sum[32];
 
     if( keylen > 64 )
@@ -394,7 +393,7 @@
 /*
  * SHA-256 HMAC process buffer
  */
-void sha2_hmac_update( sha2_context *ctx, const unsigned char *input, int ilen )
+void sha2_hmac_update( sha2_context *ctx, const unsigned char *input, size_t ilen )
 {
     sha2_update( ctx, input, ilen );
 }
@@ -431,8 +430,8 @@
 /*
  * output = HMAC-SHA-256( hmac key, input buffer )
  */
-void sha2_hmac( const unsigned char *key, int keylen,
-                const unsigned char *input, int ilen,
+void sha2_hmac( const unsigned char *key, size_t keylen,
+                const unsigned char *input, size_t ilen,
                 unsigned char output[32], int is224 )
 {
     sha2_context ctx;