diff --git a/scripts/iso/build-felhom-iso.sh b/scripts/iso/build-felhom-iso.sh
index 7011e2a..5a10340 100755
--- a/scripts/iso/build-felhom-iso.sh
+++ b/scripts/iso/build-felhom-iso.sh
@@ -162,11 +162,13 @@ else
     [[ -n "$PROFILE" ]]   || die "--profile is required"
     [[ -f "$PROFILE" ]]   || die "--profile not found: $PROFILE"
 fi
-# Mode: exactly one of --bootstrap-env (direct, secret-bearing) or --pairing (generic, secret-free).
-if $PAIRING; then
+# Mode: exactly one of --bootstrap-env (direct), --pairing (generic) or --release (public image).
+if $RELEASE; then
+    :   # validated above; a release image has no bootstrap-env by design
+elif $PAIRING; then
     [[ -z "$BOOTSTRAP_ENV" ]] || die "--pairing and --bootstrap-env are mutually exclusive"
 else
-    [[ -n "$BOOTSTRAP_ENV" ]] || die "one of --bootstrap-env (direct) or --pairing (generic) is required"
+    [[ -n "$BOOTSTRAP_ENV" ]] || die "one of --bootstrap-env (direct), --pairing (generic) or --release is required"
     [[ -f "$BOOTSTRAP_ENV" ]] || die "--bootstrap-env not found: $BOOTSTRAP_ENV"
 fi