diff --git a/datapacks/Bookshelf/data/bs.id/tests/update_cuids.mcfunction b/datapacks/Bookshelf/data/bs.id/tests/update_cuids.mcfunction
new file mode 100644
index 0000000000..9dc133b00c
--- /dev/null
+++ b/datapacks/Bookshelf/data/bs.id/tests/update_cuids.mcfunction
@@ -0,0 +1,22 @@
+# Updating cuids always returns a continuous chain
+# @batch bs.id
+
+execute summon minecraft:marker run function #bs.id:give_cuid
+execute summon minecraft:armor_stand run function #bs.id:give_cuid
+execute summon minecraft:armor_stand run function #bs.id:give_cuid
+execute summon minecraft:marker run function #bs.id:give_cuid
+execute summon minecraft:marker run function #bs.id:give_cuid
+execute summon minecraft:armor_stand run function #bs.id:give_cuid
+execute summon minecraft:marker run function #bs.id:give_cuid
+kill @e[type=minecraft:armor_stand,distance=..1]
+
+function #bs.id:update_cuids
+scoreboard players set #packtest.i bs.data 0
+execute store result score #packtest bs.data run scoreboard players operation #packtest.i bs.data > @e bs.cid
+execute as @e[type=minecraft:marker] if score @s bs.cid = #packtest.i bs.data run scoreboard players remove #packtest.i bs.data 1
+execute as @e[type=minecraft:marker] if score @s bs.cid = #packtest.i bs.data run scoreboard players remove #packtest.i bs.data 1
+execute as @e[type=minecraft:marker] if score @s bs.cid = #packtest.i bs.data run scoreboard players remove #packtest.i bs.data 1
+execute as @e[type=minecraft:marker] if score @s bs.cid = #packtest.i bs.data run scoreboard players remove #packtest.i bs.data 1
+scoreboard players operation #packtest bs.data -= #packtest.i bs.data
+kill @e[type=minecraft:marker,distance=..1]
+assert score #packtest bs.data matches 4