hash.ChecksumSHA256.String(): part.ChecksumSHA256,
			}
			if wantCS[checksumType.String()] != crc {
				return oi, InvalidPart{
					PartNumber: part.PartNumber,
					ExpETag:    wantCS[checksumType.String()],
					GotETag:    crc,
				}
			}
			cs := hash.NewChecksumString(checksumType.String(), crc)
			if !cs.Valid() {
				return oi, InvalidPart{
					PartNumber: part.PartNumber,
				}
			}