diff --git a/docs/how-to/grafana/build-grafana-container.md b/docs/how-to/grafana/build-grafana-container.md
index ccec654..08942c4 100644
--- a/docs/how-to/grafana/build-grafana-container.md
+++ b/docs/how-to/grafana/build-grafana-container.md
@@ -23,6 +23,10 @@ Grafana currently uses the upstream `docker.io/grafana/grafana:11.4.0` image via
 3. Tag and push to `forge.ops.eblu.me/eblume/grafana:<version>`
 4. Add to `mise run container-list` inventory
 
+## Lessons
+
+- **Tarball directory name:** The Grafana OSS tarball extracts to `grafana-<version>` (e.g. `grafana-12.3.3`), *not* `grafana-v<version>`. The `mv` command in the Dockerfile must match this.
+
 ## Reference
 
 - Follow [[build-container-image]] for the standard container build workflow