diff --git a/patches/server/Asynchronous-chunk-IO-and-loading.patch b/patches/server/Asynchronous-chunk-IO-and-loading.patch
index 3ee7d3b94e..ff282ad244 100644
--- a/patches/server/Asynchronous-chunk-IO-and-loading.patch
+++ b/patches/server/Asynchronous-chunk-IO-and-loading.patch
@@ -3219,6 +3219,14 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
              CompoundTag level = nbt.getCompound("Level");
              if (level.getBoolean("TerrainPopulated")) {
 @@ -0,0 +0,0 @@ public class ChunkStorage implements AutoCloseable {
+ 
+     public CompoundTag upgradeChunkTag(ResourceKey<LevelStem> resourcekey, Supplier<DimensionDataStorage> supplier, CompoundTag nbttagcompound, Optional<ResourceKey<Codec<? extends ChunkGenerator>>> optional, ChunkPos pos, @Nullable LevelAccessor generatoraccess) throws IOException {
+         // CraftBukkit end
++        nbttagcompound = nbttagcompound.copy(); // Paper - defensive copy, another thread might modify this
+         int i = ChunkStorage.getVersion(nbttagcompound);
+ 
+         // CraftBukkit start
+@@ -0,0 +0,0 @@ public class ChunkStorage implements AutoCloseable {
          if (i < 1493) {
              nbttagcompound = NbtUtils.update(this.fixerUpper, DataFixTypes.CHUNK, nbttagcompound, i, 1493);
              if (nbttagcompound.getCompound("Level").getBoolean("hasLegacyStructureData")) {