CComDate & wcscpy

I've found CComDatereally useful but when I compile I get a warning that wcscpy may be unsafe and I should use wcscpy_s

e.g.

LPTSTR CComDATE::Format(LPTSTR pszOut, DWORD dwFlags, LCID lcid) const
{
    *pszOut = 0;
    // If invalild, return empty string
    if (!IsValid()) return pszOut;
    BSTR  bstr = 0;
    if( SUCCEEDED(VarBstrFromDate(m_date, lcid, dwFlags, &bstr)) )
    {
#ifdef _UNICODE
        wcscpy(pszOut, bstr);
#else
        wcstombs(pszOut, bstr, wcslen(bstr) + 1);
#endif
        SysFreeString(bstr);
    }
    return pszOut;
}

but because this is using BSTR I'm unsure about the correct "numberOfElements" in

errno_t wcscpy_s(
   wchar_t *strDestination,
   size_t numberOfElements,
   const wchar_t *strSource 
);

is it something like sizeof(DWORD) + ( _wcslen(bstr) + 1 ) * sizeof(WCHAR)?