diff --git a/docker-compose.yml b/docker-compose.yml
index 313b23e0..0fc5a211 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -107,6 +107,11 @@ services:
 
   redis:
     image: redis:7-alpine
+    # In memory. The image declares a volume at /data, so without a mount there each new
+    # container got a new anonymous volume, which `docker compose down` left behind. Redis holds
+    # only the broker's queue and the app's short-lived keys, which it can lose.
+    tmpfs:
+      - /data
     healthcheck:
       test: ["CMD", "redis-cli", "ping"]
       interval: 5s
diff --git a/scripts/local_sanitize_backup.sh b/scripts/local_sanitize_backup.sh
index 4dcf59b4..818c6169 100755
--- a/scripts/local_sanitize_backup.sh
+++ b/scripts/local_sanitize_backup.sh
@@ -78,7 +78,9 @@ DB_URL="postgres://postgres:postgres@localhost:${PORT}/${DB_NAME}"
 cleanup() {
   if [[ $CONTAINER_STARTED -eq 1 ]]; then
     echo "Stopping container ${CONTAINER}..."
-    docker rm -f "$CONTAINER" >/dev/null 2>&1 || true
+    # -v: --rm deletes the data volume only when the container stops on its own, and removing
+    # it here would otherwise leave a copy of the restored database behind.
+    docker rm -f -v "$CONTAINER" >/dev/null 2>&1 || true
   fi
 }
 trap cleanup EXIT
diff --git a/scripts/test_download_s3_dump.sh b/scripts/test_download_s3_dump.sh
index 6ac91032..2134caa8 100755
--- a/scripts/test_download_s3_dump.sh
+++ b/scripts/test_download_s3_dump.sh
@@ -25,7 +25,8 @@ LARGE_DUMP_BYTES=$((9 * 1024 * 1024))
 run="qb-s3-dump-test-$$"
 work="$(mktemp -d)"
 cleanup() {
-  docker rm -f "$run-s3" "$run-pg18" "$run-pg17" >/dev/null 2>&1 || true
+  # -v: with their anonymous volumes, such as each Postgres's data directory.
+  docker rm -f -v "$run-s3" "$run-pg18" "$run-pg17" >/dev/null 2>&1 || true
   rm -rf "$work"
 }
 trap cleanup EXIT