diff --git a/README.md b/README.md
index bd58a0b..9936c32 100644
--- a/README.md
+++ b/README.md
@@ -14,3 +14,11 @@ Key behavior:
 
 Trigger manually in Jenkins when a new Harbor version needs to be published to
 the internal registry.
+
+## Running a test build
+- In Jenkins, run the `harbor-arm-build` job (leave `HARBOR_VERSION` blank to
+  build the latest upstream release).
+- The agent pulls Harbor sources, builds every component for arm64, and pushes
+  the tagged artifacts to `registry.bstein.dev/infra`.
+- Verify the images appear in Harbor under the `infra` project with the
+  `${HARBOR_VERSION}-arm64.$BUILD_NUMBER` tag suffix.