diff --git a/postgresql/cutover/test/pgha-dryrun.yaml b/postgresql/cutover/test/pgha-dryrun.yaml
index 44f6d5a..008d49a 100644
--- a/postgresql/cutover/test/pgha-dryrun.yaml
+++ b/postgresql/cutover/test/pgha-dryrun.yaml
@@ -17,6 +17,14 @@
 # interpolation parses $( as an attempted ${VAR} reference and fails with
 # "invalid interpolation format" / "you may need to escape any $ with
 # another $". $$ escapes to a literal $ for the shell at runtime.
+#
+# NOTE: ETCD3_HOSTS not ETCD_HOSTS — confirmed against zalando/spilo
+# configure_spilo.py: PATRONI_DCS includes both "etcd" (legacy v2 API,
+# python-etcd client) and "etcd3" (v3 API, python-etcd3 client) as
+# distinct DCS backends selected by env var prefix. Our etcd containers
+# (v3.5.9) have the v2 API disabled by default, so ETCD_HOSTS causes
+# Patroni to hit /v2 endpoints that 404. ETCD3_HOSTS selects the correct
+# v3-API client.
 # ─────────────────────────────────────────────────────────────────────────
 version: "3.6"
 
@@ -128,7 +136,7 @@ services:
     environment:
       SCOPE: pgha-test
       PATRONI_NAME: patroni-0
-      ETCD_HOSTS: '"etcd-1:2379","etcd-2:2379","etcd-3:2379"'
+      ETCD3_HOSTS: '"etcd-1:2379","etcd-2:2379","etcd-3:2379"'
       PGUSER_SUPERUSER: PGadmin
       PGUSER_STANDBY: standby
       PATRONI_RESTAPI_USERNAME: patroni
@@ -166,7 +174,7 @@ services:
     environment:
       SCOPE: pgha-test
       PATRONI_NAME: patroni-1
-      ETCD_HOSTS: '"etcd-1:2379","etcd-2:2379","etcd-3:2379"'
+      ETCD3_HOSTS: '"etcd-1:2379","etcd-2:2379","etcd-3:2379"'
       PGUSER_SUPERUSER: PGadmin
       PGUSER_STANDBY: standby
       PATRONI_RESTAPI_USERNAME: patroni