diff --git a/lib/libmd5sum/md5.c b/lib/libmd5sum/md5.c
index aece50d10..40ff825da 100644
--- a/lib/libmd5sum/md5.c
+++ b/lib/libmd5sum/md5.c
@@ -216,13 +216,14 @@ md5_process_bytes (buffer, len, ctx)
       memmove (&ctx->buffer[left_over], buffer, add);
       ctx->buflen += add;
 
-      if (left_over + add > 64)
+      if (ctx->buflen > 64)
 	{
-	  md5_process_block (ctx->buffer, (left_over + add) & ~63, ctx);
+	  md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
+
+	  ctx->buflen &= 63;
 	  /* The regions in the following copy operation cannot overlap.  */
 	  memmove (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
-		  (left_over + add) & 63);
-	  ctx->buflen = (left_over + add) & 63;
+		  ctx->buflen);
 	}
 
       buffer = (const char *) buffer + add;
@@ -230,18 +231,46 @@ md5_process_bytes (buffer, len, ctx)
     }
 
   /* Process available complete blocks.  */
-  if (len > 64)
+  if (len >= 64)
     {
-      md5_process_block (buffer, len & ~63, ctx);
-      buffer = (const char *) buffer + (len & ~63);
-      len &= 63;
+#if !_STRING_ARCH_unaligned
+/* To check alignment gcc has an appropriate operator.  Other
+   compilers don't.  */
+# if __GNUC__ >= 2
+#  define UNALIGNED_P(p) (((md5_uintptr) p) % __alignof__ (md5_uint32) != 0)
+# else
+#  define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)
+# endif
+      if (UNALIGNED_P (buffer))
+	while (len > 64)
+	  {
+	    md5_process_block (memmove (ctx->buffer, buffer, 64), 64, ctx);
+	    buffer = (const char *) buffer + 64;
+	    len -= 64;
+	  }
+      else
+#endif
+	{
+	  md5_process_block (buffer, len & ~63, ctx);
+	  buffer = (const char *) buffer + (len & ~63);
+	  len &= 63;
+	}
     }
 
   /* Move remaining bytes in internal buffer.  */
   if (len > 0)
     {
-      memmove (ctx->buffer, buffer, len);
-      ctx->buflen = len;
+      size_t left_over = ctx->buflen;
+
+      memmove (&ctx->buffer[left_over], buffer, len);
+      left_over += len;
+      if (left_over >= 64)
+	{
+	  md5_process_block (ctx->buffer, 64, ctx);
+	  left_over -= 64;
+	  memmove (ctx->buffer, &ctx->buffer[64], left_over);
+	}
+      ctx->buflen = left_over;
     }
 }
 
diff --git a/lib/libmd5sum/md5.h b/lib/libmd5sum/md5.h
index ad97efc32..ba1157d76 100644
--- a/lib/libmd5sum/md5.h
+++ b/lib/libmd5sum/md5.h
@@ -35,14 +35,11 @@
    is usually not possible.  */
 
 #ifdef _LIBC
-# include <sys/types.h>
-typedef u_int32_t md5_uint32;
+# include <stdint.h>
+typedef uint32_t md5_uint32;
+typedef uintptr_t md5_uintptr;
 #else
-# if defined __STDC__ && __STDC__
-#  define UINT_MAX_32_BITS 4294967295U
-# else
-#  define UINT_MAX_32_BITS 0xFFFFFFFF
-# endif
+# define UINT_MAX_32_BITS 4294967295U
 
 /* If UINT_MAX isn't defined, assume it's a 32-bit type.
    This should be valid for all systems GNU cares about because
@@ -63,11 +60,14 @@ typedef u_int32_t md5_uint32;
      typedef unsigned long md5_uint32;
 #   else
      /* The following line is intended to evoke an error.
-        Using #error is not portable enough.  */
+	Using #error is not portable enough.  */
      "Cannot determine unsigned 32-bit data type."
 #   endif
 #  endif
 # endif
+/* We have to make a guess about the integer type equivalent in size
+   to pointers which should always be correct.  */
+typedef unsigned long int md5_uintptr;
 #endif
 
 #undef __P