Hello delphizip, On checking a zipfile I end up with a negative result (eg count is lower than successcount): with ZipMaster1 do begin if Count = SuccessCnt then ShowMessage('All ' + IntToStr(Count) + ' files tested OK') else ShowMessage('Files tested: ' + inttostr(count) + chr(13) + chr(10) + 'ERROR: ' + IntToStr(Count - SuccessCnt) + ' files tested as bad, or skipped!'); end; In fact with another test program the same zip file CRC check is OK. (zipmaster=) fSuccessCnt := UnzDLLExec(Pointer(UnZipParms.up1)); count (I think) comes from UnzipParms.up2^ .count -- Regards, Alistair+