PVS-Studio warning V555 for PHP

static int strfilter_convert_append_bucket(
{
  size_t out_buf_size;
  ....
  size_t ocnt, icnt, tcnt;
  ....
  if (out_buf_size - ocnt > 0) { //<==
    ....
    php_stream_bucket_append(buckets_out, new_bucket TSRMLS_CC);
  } else {
    pefree(out_buf, persistent);
  }
  ....
}

This suspicious code was found in PHP project by PVS-Studio static code analyzer.
Warning message is:
V555 The expression 'out_buf_size - ocnt > 0' will work as 'out_buf_size != ocnt'. filters.c 1702

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