diff --git a/README.md b/README.md
index e2694d9..ed5c26e 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,11 @@ The forgejo-test-helper.sh script is available to help test and debug actions.
   Create the repository `$forgejo/root/testrepo` and populate it with the
   content of the `testrepo` directory. The SHA of the tip of the repository
   is in the output, starting with `sha=`.
+* `forgejo-test-helper.sh build_runner $forgejo/forgejo/runner v1.4.1`
+  Builds the forgejo runner from source in `./forgejo-runner/forgejo-runner`.
+  `export PATH=$(pwd)/forgejo-runner:$PATH` will ensure that calling `forgejo-runner.sh`
+  will use this binary instead of downloading a released version of the runner.
+  If the version is not specified, build from the main branch.
 
 The combination of `push_self_action` and `run_workflow` allows to
 run Forgejo Actions workflows from `testrepo` that use the action
@@ -55,6 +60,7 @@ It can only be run on the `self-hosted` platform, running on a host with LXC ins
 | host-port | Host and port of the Forgejo instance, e.g 172.0.17.2:3000 |
 | token | Administrator application token with all,sudo scopes |
 | runner-logs | Filename of the Forgejo runner logs |
+| runner-file | Path to the runner file |
 <!-- action-docs-outputs -->
 
 ## Example