diff --git a/amulet/level/formats/anvil_world/format.py b/amulet/level/formats/anvil_world/format.py
index b760640d2..dafabf064 100644
--- a/amulet/level/formats/anvil_world/format.py
+++ b/amulet/level/formats/anvil_world/format.py
@@ -495,12 +495,12 @@ def pre_save_operation(
         except StopIteration as e:
             height_changed = e.value
 
-        # light = self._calculate_light(level, changed_chunks)
-        # try:
-        #     while True:
-        #         yield next(light) / 2
-        # except StopIteration as e:
-        #     light_changed = e.value
+        light = self._calculate_light(level, changed_chunks)
+        try:
+            while True:
+                yield next(light) / 2
+        except StopIteration as e:
+            light_changed = e.value
 
         return height_changed  # or light_changed
 
@@ -539,11 +539,24 @@ def _calculate_light(
         changed = False
         if level.level_wrapper.version < 1934:
             # the version may be less than 1934 but is at least 1924
-            # calculate the light values
+            # TODO need to calculate the light values for 1,12 > 1.13.
+            # for i, (dimension, cx, cz) in enumerate(chunks):
+            #     try:
+            #         chunk = level.get_chunk(cx, cz, dimension)
+            #     except ChunkLoadError:
+            #         pass
+            #     else:
+            #         changed_ = False
+            #         changed_ |= chunk.misc.pop("block_light", None) is not None Needs better 
+            #         changed_ |= chunk.misc.pop("sky_light", None) is not None
+            #         if changed_:
+            #             changed = True
+            #             chunk.changed = True
+            #     yield i / chunk_count
             pass
-            # TODO
         else:
             # the game will recalculate the light levels
+            # applies to versions (19w08b) 1934 to 3949 (1.21.Pre2)
             for i, (dimension, cx, cz) in enumerate(chunks):
                 try:
                     chunk = level.get_chunk(cx, cz, dimension)
@@ -551,8 +564,7 @@ def _calculate_light(
                     pass
                 else:
                     changed_ = False
-                    changed_ |= chunk.misc.pop("block_light", None) is not None
-                    changed_ |= chunk.misc.pop("sky_light", None) is not None
+                    changed_ |= chunk.misc.pop("isLightOn", None) is not None
                     if changed_:
                         changed = True
                         chunk.changed = True
diff --git a/amulet/level/interfaces/chunk/anvil/anvil_1934.py b/amulet/level/interfaces/chunk/anvil/anvil_1934.py
index bb13f74d7..b19bd0b68 100644
--- a/amulet/level/interfaces/chunk/anvil/anvil_1934.py
+++ b/amulet/level/interfaces/chunk/anvil/anvil_1934.py
@@ -1,17 +1,51 @@
 from __future__ import annotations
 
+from typing import List, Tuple, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from amulet.api.chunk import Chunk
+
+from amulet_nbt import CompoundTag, ByteTag
+
+from .base_anvil_interface import ChunkDataType, ChunkPathType
+
 from .anvil_1912 import Anvil1912Interface as ParentInterface
 
 
 class Anvil1934Interface(ParentInterface):
+    isLightOn: ChunkPathType = (
+        "region",
+        [("Level", CompoundTag), ("isLightOn", ByteTag)],
+        ByteTag,
+    )
     """
     Made lighting optional
+    Made game recalculate lighting 
     """
 
     def __init__(self):
         super().__init__()
         self._set_feature("light_optional", "true")
 
+        self._register_decoder(self._decode_islighton)
+        self._register_encoder(self._encode_islighton)
+
+    def _decode_islighton(
+        self, chunk: Chunk, data: ChunkDataType, floor_cy: int, height_cy: int
+    ):
+        chunk.misc["isLightOn"] = self.get_layer_obj(
+            data, self.isLightOn, pop_last=True
+        )
+
+    def _encode_islighton(
+        self, chunk: Chunk, data: ChunkDataType, floor_cy: int, height_cy: int
+    ):
+        self.set_layer_obj(
+            data,
+            self.isLightOn,
+            chunk.misc.get("isLightOn", None),
+        )
+
     @staticmethod
     def minor_is_valid(key: int):
         return 1934 <= key < 2203
diff --git a/amulet/level/interfaces/chunk/anvil/anvil_2844.py b/amulet/level/interfaces/chunk/anvil/anvil_2844.py
index 6c21c0018..24991e7a9 100644
--- a/amulet/level/interfaces/chunk/anvil/anvil_2844.py
+++ b/amulet/level/interfaces/chunk/anvil/anvil_2844.py
@@ -57,7 +57,7 @@ class Anvil2844Interface(ParentInterface):
     OldLevel: ChunkPathType = ("region", [("Level", CompoundTag)], CompoundTag)
     Level: ChunkPathType = ("region", [], CompoundTag)
     Sections: ChunkPathType = ("region", [("sections", ListTag)], ListTag)
-
+    isLightOn: ChunkPathType = ("region", [("isLightOn", ByteTag)], ByteTag)
     Entities: ChunkPathType = ("region", [("entities", ListTag)], ListTag)
     BlockEntities: ChunkPathType = ("region", [("block_entities", ListTag)], ListTag)
     BlockTicks: ChunkPathType = ("region", [("block_ticks", ListTag)], ListTag)