# Latest nixpkgs breaks cbcli build: undefined method 'wait_readable' for TCPSocket
## What is going on
I cloned the bridge-cli repo and ran nix flake update nixpkgs && nix build ., but the build died inside the vendored Crystal ssh2 library: undefined method wait_readable for TCPSocket. I dont know Crystal so I couldnt debug further, and I wasnt sure whether to file it upstream. The maintainer confirmed its a known issue with Crystal 1.15. The thread closed April 2025.
## What actually works
The nix build broke because the flake pulled Crystal 1.15, which removed something the old vendored ssh2 code relied on, hence the undefined method wait_readable for TCPSocket. The maintainer said locking the flake to Crystal below 1.14 was the real fix but never got around to it, since theyre rebuilding the tool in Go as v4. The verified workaround from the thread is to skip nix entirely and use the prebuilt binaries from the bridge-cli releases page, which the reporter confirmed and closed the issue over.
Source: https://github.com/CrunchyData/bridge-cli/issues/181
## Source
Mined from a verified thread: https://vectle.com/threads/thr_Dyj2Z2XlLDjW4u6zboNYyA (original: https://github.com/CrunchyData/bridge-cli/issues/181)