diff --git a/cipher/hash-common.c b/cipher/hash-common.c
index a750d644..74675d49 100644
--- a/cipher/hash-common.c
+++ b/cipher/hash-common.c
@@ -1,167 +1,185 @@
 /* hash-common.c - Common code for hash algorithms
  * Copyright (C) 2008 Free Software Foundation, Inc.
  *
  * This file is part of Libgcrypt.
  *
  * Libgcrypt is free software; you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as
  * published by the Free Software Foundation; either version 2.1 of
  * the License, or (at your option) any later version.
  *
  * Libgcrypt is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this program; if not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <config.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #ifdef HAVE_STDINT_H
 # include <stdint.h>
 #endif
 
 #include "g10lib.h"
+#include "bufhelp.h"
 #include "hash-common.h"
 
 
 /* Run a selftest for hash algorithm ALGO.  If the resulting digest
    matches EXPECT/EXPECTLEN and everything else is fine as well,
    return NULL.  If an error occurs, return a static text string
    describing the error.
 
    DATAMODE controls what will be hashed according to this table:
 
      0 - Hash the supplied DATA of DATALEN.
      1 - Hash one million times a 'a'.  DATA and DATALEN are ignored.
 
 */
 const char *
 _gcry_hash_selftest_check_one (int algo,
                                int datamode, const void *data, size_t datalen,
                                const void *expect, size_t expectlen)
 {
   const char *result = NULL;
   gcry_error_t err = 0;
   gcry_md_hd_t hd;
   unsigned char *digest;
   char aaa[1000];
   int xof = 0;
 
   if (_gcry_md_get_algo_dlen (algo) == 0)
     xof = 1;
   else if (_gcry_md_get_algo_dlen (algo) != expectlen)
     return "digest size does not match expected size";
 
   err = _gcry_md_open (&hd, algo, 0);
   if (err)
     return "gcry_md_open failed";
 
   switch (datamode)
     {
     case 0:
       _gcry_md_write (hd, data, datalen);
       break;
 
     case 1: /* Hash one million times an "a". */
       {
         int i;
 
         /* Write in odd size chunks so that we test the buffering.  */
         memset (aaa, 'a', 1000);
         for (i = 0; i < 1000; i++)
           _gcry_md_write (hd, aaa, 1000);
       }
       break;
 
     default:
       result = "invalid DATAMODE";
     }
 
   if (!result)
     {
       if (!xof)
 	{
 	  digest = _gcry_md_read (hd, algo);
 
 	  if ( memcmp (digest, expect, expectlen) )
 	    result = "digest mismatch";
 	}
       else
 	{
 	  gcry_assert(expectlen <= sizeof(aaa));
 
 	  err = _gcry_md_extract (hd, algo, aaa, expectlen);
 	  if (err)
 	    result = "error extracting output from XOF";
 	  else if ( memcmp (aaa, expect, expectlen) )
 	    result = "digest mismatch";
 	}
     }
 
   _gcry_md_close (hd);
 
   return result;
 }
 
 
 /* Common function to write a chunk of data to the transform function
    of a hash algorithm.  Note that the use of the term "block" does
    not imply a fixed size block.  Note that we explicitly allow to use
    this function after the context has been finalized; the result does
    not have any meaning but writing after finalize is sometimes
    helpful to mitigate timing attacks. */
 void
 _gcry_md_block_write (void *context, const void *inbuf_arg, size_t inlen)
 {
   const unsigned char *inbuf = inbuf_arg;
   gcry_md_block_ctx_t *hd = context;
   unsigned int stack_burn = 0;
+  unsigned int nburn;
   const unsigned int blocksize = hd->blocksize;
   size_t inblocks;
+  size_t copylen;
 
   if (sizeof(hd->buf) < blocksize)
     BUG();
 
   if (!hd->bwrite)
     return;
 
-  if (hd->count == blocksize)  /* Flush the buffer. */
+  while (hd->count)
     {
-      stack_burn = hd->bwrite (hd, hd->buf, 1);
-      _gcry_burn_stack (stack_burn);
-      stack_burn = 0;
-      hd->count = 0;
-      if (!++hd->nblocks)
-        hd->nblocks_high++;
-    }
-  if (!inbuf)
-    return;
+      if (hd->count == blocksize)  /* Flush the buffer. */
+	{
+	  nburn = hd->bwrite (hd, hd->buf, 1);
+	  stack_burn = nburn > stack_burn ? nburn : stack_burn;
+	  hd->count = 0;
+	  if (!++hd->nblocks)
+	    hd->nblocks_high++;
+	}
+      else
+	{
+	  copylen = inlen;
+	  if (copylen > blocksize - hd->count)
+	    copylen = blocksize - hd->count;
 
-  if (hd->count)
-    {
-      for (; inlen && hd->count < blocksize; inlen--)
-        hd->buf[hd->count++] = *inbuf++;
-      _gcry_md_block_write (hd, NULL, 0);
-      if (!inlen)
-        return;
+	  if (copylen == 0)
+	    break;
+
+	  buf_cpy (&hd->buf[hd->count], inbuf, copylen);
+	  hd->count += copylen;
+	  inbuf += copylen;
+	  inlen -= copylen;
+	}
     }
 
+  if (inlen == 0)
+    return;
+
   if (inlen >= blocksize)
     {
       inblocks = inlen / blocksize;
-      stack_burn = hd->bwrite (hd, inbuf, inblocks);
+      nburn = hd->bwrite (hd, inbuf, inblocks);
+      stack_burn = nburn > stack_burn ? nburn : stack_burn;
       hd->count = 0;
       hd->nblocks_high += (hd->nblocks + inblocks < inblocks);
       hd->nblocks += inblocks;
       inlen -= inblocks * blocksize;
       inbuf += inblocks * blocksize;
     }
-  _gcry_burn_stack (stack_burn);
-  for (; inlen && hd->count < blocksize; inlen--)
-    hd->buf[hd->count++] = *inbuf++;
+
+  if (inlen)
+    {
+      buf_cpy (hd->buf, inbuf, inlen);
+      hd->count = inlen;
+    }
+
+  if (stack_burn > 0)
+    _gcry_burn_stack (stack_burn);
 }