diff --git a/amulet/level/interfaces/chunk/anvil/anvil_3463.py b/amulet/level/interfaces/chunk/anvil/anvil_3463.py
index 56a9bcf08..35ea563a2 100644
--- a/amulet/level/interfaces/chunk/anvil/anvil_3463.py
+++ b/amulet/level/interfaces/chunk/anvil/anvil_3463.py
@@ -13,7 +13,7 @@ def __init__(self):
 
     @staticmethod
     def minor_is_valid(key: int):
-        return 3454 <= key <= 3900
+        return 3454 <= key <= 4000
 
 
 export = Anvil3463Interface