diff --git a/scripts/install-image-efi.sh b/scripts/install-image-efi.sh
index 9537ad98..ed5067f9 100755
--- a/scripts/install-image-efi.sh
+++ b/scripts/install-image-efi.sh
@@ -65,7 +65,7 @@ BUSYBOX="${BUSYBOX:-$ROOTFS/bin/busybox}"
 for t in sfdisk mke2fs cpio gzip; do command -v "$t" >/dev/null 2>&1 || { echo "falta $t" >&2; exit 1; }; done
 unshare -r true 2>/dev/null || { echo "se requiere 'unshare -r' (ficheros root-owned sin sudo)" >&2; exit 1; }
 
-STAGE="work/.install-efi-stage"
+STAGE="${STAGE:-work/.install-efi-stage}"
 rm -rf "$STAGE"; mkdir -p "$STAGE"
 ROOT_TREE="$STAGE/root"
 IRD_TREE="$STAGE/initramfs"