diff --git a/scripts/fuse-tar-root b/scripts/fuse-tar-root
index 4946bd0c..1da4e3f6 100644
--- a/scripts/fuse-tar-root
+++ b/scripts/fuse-tar-root
@@ -21,7 +21,7 @@
 
 ROOT_PARTITION=${ROOT_PARTITION:-1}
 ROOT_MOUNT=${TMP_DIR}/root
-DETECT_BLS_BOOT=${DETECT_BLS_BOOT:0}
+DETECT_BLS_BOOT=${DETECT_BLS_BOOT:-0}
 BOOT_MOUNT=${TMP_DIR}/boot
 
 echo 'Mounting root partition...'