I'm trying to download the Olson time-zone database so Chronos can automatically update its ruleset. In a workspace, when I do: ZnClient new url:'http://www.iana.org/time-zones/repository/tzdata-latest.tar.gz'; downloadTo:FileDirectory default pathName. I get a SubscriptOutOfBounds error . The file is ~207kB. The GzipReadStream>#getFirstBuffer gets the first 65,536 bytes and then hits the out of bounds error. Moving the limit in that method to 262,144 (1 << 18 rather than 1 << 16) gets us to another error from which I don't know the right way to proceed. I think that because its an content type 'application/x-tar' it shouldn't hit the GzipReadStream class at all but should just be a ReadStream that does not get decompressed in the image and instead sent straight to the disk. I'm not sure how to implement that though inside Zinc and would welcome ideas to try. Thanks Paul