I came across a strange bug in the code to do MD4 checksums, which I had nicked from rsync. Never use other people's code without reading it thoroughly :-(. The bug didn't actually hurt much, because while it got all the block checksums wrong, it did so consistently, so zsync was happy. But it's a bug, and 0.0.5 fixes it.
Unfortunately that means the checksums have changed incompatibly. So zsync-0.0.5 is not backwards compatible with older streams, and zsync-0.0.4 will not work with newer streams. It's 0.0.x, if you were relying on the format then tough. I have changed all the URLs on the streams page so there should be as little confusion as possible.
Also this version doesn't miss matches at the end of the stream, and it should compile at least on Solaris. And you really need OpenSSL now (whereas before it was used only for the optional SHA-1 checksums). Sorry.