Jupyter-notebook kernel not working on jupyter lab

In reference to

I’m fixing up the jupyter-wire framework for creating kernels with dlang. The kernels appear to work with jupyter-notebook, but with jupyter-lab, the connection state stays unknown and the kernel appears not to respond. I’ve looked at the debug logs, and the kernel does seem to be communicating with jupyter-lab.

Any ideas for what is different between jupyter notebook and jupyter lab? I assume that jupyter notebook kernels should work on jupyterlab automatically.