diff --git a/deploy/build.sh b/deploy/build.sh
index b65f7ff..85980e5 100755
--- a/deploy/build.sh
+++ b/deploy/build.sh
@@ -26,7 +26,7 @@ BUILD_IMAGE="${BUILD_IMAGE:-localhost/ctao-portal-build:1}"
 BUILD_NETNS="${BUILD_NETNS:-container:ctao-demo-gitea}"
 CODE_URL="${CODE_URL:-http://localhost:3000/$CODE_REPO.git}"
 CONTENT_URL="${CONTENT_URL:-http://localhost:3000/$CONTENT_REPO.git}"
-KEEP="${KEEP:-3}"                                 # released builds to retain
+KEEP="${KEEP:-3}"                                 # previous releases kept besides `current` (rollback targets)
 mkdir -p "$BASE/repo" "$BASE/content" "$BASE/releases" "$BASE/state" "$BASE/npm-cache"
 
 # Host prerequisites (everything else runs inside containers). Fail loud —