diff --git a/docs/developer.md b/docs/developer.md
index 6e0fc33c8..59fbe09a2 100644
--- a/docs/developer.md
+++ b/docs/developer.md
@@ -237,9 +237,11 @@ kubectl logs acid-minimal-cluster-0
 
 ## End-to-end tests
 
-The operator provides reference end-to-end tests (e2e) (as Docker image) to
-ensure various infrastructure parts work smoothly together. Each e2e execution
-tests a Postgres Operator image built from the current git branch. The test
+The operator provides reference end-to-end (e2e) tests to
+ensure various infrastructure parts work smoothly together. The test code is available at `e2e/tests`.
+The special `registry.opensource.zalan.do/acid/postgres-operator-e2e-tests-runner` image is used to run the tests. The container mounts the local `e2e/tests` directory at runtime, so whatever you modify in your local copy of the tests will be executed by a test runner. By maintaining a separate test runner image we avoid the need to re-build the e2e test image on every build. 
+
+Each e2e execution tests a Postgres Operator image built from the current git branch. The test
 runner creates a new local K8s cluster using [kind](https://kind.sigs.k8s.io/),
 utilizes provided manifest examples, and runs e2e tests contained in the `tests`
 folder. The K8s API client in the container connects to the `kind` cluster via