diff --git a/docs/HACKING.md b/docs/HACKING.md
index 1d66e1e..b052d9a 100644
--- a/docs/HACKING.md
+++ b/docs/HACKING.md
@@ -101,3 +101,24 @@ And provide information requested
 ```bash
 make
 ```
+
+## Troubleshooting
+
+### Permission denied (publickey) in `make env`
+
+`make env` runs `./integration/ci.sh init` which bootstraps a local
+Gitea instance with some repositories for running tests. It also adds a
+deploy SSH key, with read/write access to those repositories.
+
+Please ensure the following:
+
+1. The private key at [tests/fleet-deploy-key](../tests/fleet-deploy-key)
+   has `600` permissions. If not:
+
+```bash
+chmod 600 tests/fleet-deploy-key
+```
+
+2. The Gitea instance listens at port 22, ensure it is listening on that
+   port. This can be verified by checking for orphan Gitea instances
+   and/or SSH daemons on that port.(TODO: listen SSH on different port)