diff --git a/library/ccm.c b/library/ccm.c
index 3edfba3..7bf9e9f 100644
--- a/library/ccm.c
+++ b/library/ccm.c
@@ -112,7 +112,6 @@
                               const unsigned char *input,
                               unsigned char *output )
 {
-    size_t i;
     size_t olen = 0;
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char tmp_buf[16] = {0};
@@ -125,8 +124,7 @@
         return ret;
     }
 
-    for( i = 0; i < use_len; i++ )
-        output[i] = input[i] ^ tmp_buf[offset + i];
+    mbedtls_xor( output, input, tmp_buf + offset, use_len );
 
     mbedtls_platform_zeroize(tmp_buf, sizeof(tmp_buf));
     return ret;
@@ -269,7 +267,6 @@
                            size_t add_len )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
-    unsigned char i;
     size_t olen, use_len, offset;
 
     if( ctx->state & CCM_STATE__ERROR )
@@ -310,8 +307,7 @@
             if( use_len > add_len )
                 use_len = add_len;
 
-            for( i = 0; i < use_len; i++ )
-                ctx->y[i + offset] ^= add[i];
+            mbedtls_xor( ctx->y + offset, ctx->y + offset, add, use_len );
 
             ctx->processed += use_len;
             add_len -= use_len;
@@ -381,8 +377,7 @@
         if( ctx->mode == MBEDTLS_CCM_ENCRYPT || \
             ctx->mode == MBEDTLS_CCM_STAR_ENCRYPT )
         {
-            for( i = 0; i < use_len; i++ )
-                ctx->y[i + offset] ^= input[i];
+            mbedtls_xor( ctx->y + offset, ctx->y + offset, input, use_len );
 
             if( use_len + offset == 16 || ctx->processed == ctx->plaintext_len )
             {
@@ -411,8 +406,7 @@
             if( ret != 0 )
                 goto exit;
 
-            for( i = 0; i < use_len; i++ )
-                ctx->y[i + offset] ^= local_output[i];
+            mbedtls_xor( ctx->y + offset, ctx->y + offset, local_output, use_len );
 
             memcpy( output, local_output, use_len );
             mbedtls_platform_zeroize( local_output, 16 );