diff --git a/build.gradle b/build.gradle
index 0be21ae8c..c6287584c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -55,8 +55,8 @@ dependencies {
     testImplementation 'org.junit.jupiter:junit-jupiter-params:5.7.0'
     testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.7.0'
 
-    modRuntime "me.shedaniel:RoughlyEnoughItems-api:5.2.10"
-    modRuntime "me.shedaniel:RoughlyEnoughItems:5.2.10"
+    modRuntime "me.shedaniel:RoughlyEnoughItems-api:5.8.9"
+    modRuntime "me.shedaniel:RoughlyEnoughItems:5.8.9"
 }
 
 sourceSets {
diff --git a/gradle.properties b/gradle.properties
index 8be827870..430289d0e 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -5,13 +5,13 @@ org.gradle.jvmargs=-Xmx1G
 mod_version=1.95.1-beta
 
 # Minecraft properties
-mc_version=1.16.2
-mappings_version=31
+mc_version=1.16.4
+mappings_version=9
 
 # Dependencies
 cloth_config_version=4.8.1
-fabric_api_version=0.19.0+build.398-1.16
-fabric_loader_version=0.9.2+build.206
+fabric_api_version=0.34.2+1.16
+fabric_loader_version=0.11.3
 jankson_version=1.2.0
 modmenu_version=1.14.6+
 cloth_api_version=1.4.5
diff --git a/patchwork.md b/patchwork.md
index ccda58db5..c413af097 100644
--- a/patchwork.md
+++ b/patchwork.md
@@ -590,4 +590,11 @@ c864576619751077a0d8ac1a18123e14b095ec03
 
 Fix impostor recipes for disks
 ```
-[TODO] [JUMT-03] REI still shows white disks, probably because it doesn' show nbt items.
\ No newline at end of file
+[TODO] [JUMT-03] REI still shows white disks, probably because it doesn' show nbt items.
+
+```
+c5694ea9661c7a40021ebd280c378bd7bdc56988
+
+Merge branch 'mc-1.15.x' into mc-1.16.x
+```
+Update to 1.16.4.
\ No newline at end of file
diff --git a/src/main/java/dan200/computercraft/api/turtle/FakePlayer.java b/src/main/java/dan200/computercraft/api/turtle/FakePlayer.java
index 76656fa78..4eac506e4 100644
--- a/src/main/java/dan200/computercraft/api/turtle/FakePlayer.java
+++ b/src/main/java/dan200/computercraft/api/turtle/FakePlayer.java
@@ -48,7 +48,7 @@ import net.minecraft.util.Hand;
 import net.minecraft.util.collection.DefaultedList;
 import net.minecraft.util.math.ChunkPos;
 import net.minecraft.util.math.Vec3d;
-import net.minecraft.village.TraderOfferList;
+import net.minecraft.village.TradeOfferList;
 import net.minecraft.world.GameMode;
 
 /**
@@ -105,7 +105,7 @@ public class FakePlayer extends ServerPlayerEntity {
     }
 
     @Override
-    public void sendTradeOffers(int id, TraderOfferList list, int level, int experience, boolean levelled, boolean refreshable) { }
+    public void sendTradeOffers(int id, TradeOfferList list, int level, int experience, boolean levelled, boolean refreshable) { }
 
     @Override
     public void openHorseInventory(HorseBaseEntity horse, Inventory inventory) { }
@@ -251,10 +251,6 @@ public class FakePlayer extends ServerPlayerEntity {
         public void disconnect(Text message) {
         }
 
-        @Override
-        public void setupEncryption(SecretKey key) {
-        }
-
         @Override
         public void disableAutoRead() {
         }
diff --git a/src/main/java/dan200/computercraft/mixin/MixinWorld.java b/src/main/java/dan200/computercraft/mixin/MixinWorld.java
index 04b45e796..be271fca2 100644
--- a/src/main/java/dan200/computercraft/mixin/MixinWorld.java
+++ b/src/main/java/dan200/computercraft/mixin/MixinWorld.java
@@ -32,7 +32,7 @@ public class MixinWorld {
 
     @Inject (method = "setBlockEntity", at = @At ("HEAD"))
     public void setBlockEntity(BlockPos pos, @Nullable BlockEntity entity, CallbackInfo info) {
-        if (!World.isHeightInvalid(pos) && entity != null && !entity.isRemoved() && this.iteratingTickingBlockEntities) {
+        if (!World.isOutOfBuildLimitVertically(pos) && entity != null && !entity.isRemoved() && this.iteratingTickingBlockEntities) {
             setWorld(entity, this);
         }
     }
diff --git a/src/main/java/dan200/computercraft/shared/BundledRedstone.java b/src/main/java/dan200/computercraft/shared/BundledRedstone.java
index dec3f0bf7..2e53b20b0 100644
--- a/src/main/java/dan200/computercraft/shared/BundledRedstone.java
+++ b/src/main/java/dan200/computercraft/shared/BundledRedstone.java
@@ -31,7 +31,7 @@ public final class BundledRedstone {
     }
 
     public static int getDefaultOutput(@Nonnull World world, @Nonnull BlockPos pos, @Nonnull Direction side) {
-        return World.method_24794(pos) ? DefaultBundledRedstoneProvider.getDefaultBundledRedstoneOutput(world, pos, side) : -1;
+        return World.isValid(pos) ? DefaultBundledRedstoneProvider.getDefaultBundledRedstoneOutput(world, pos, side) : -1;
     }
 
     public static int getOutput(World world, BlockPos pos, Direction side) {
@@ -40,7 +40,7 @@ public final class BundledRedstone {
     }
 
     private static int getUnmaskedOutput(World world, BlockPos pos, Direction side) {
-        if (!World.method_24794(pos)) {
+        if (!World.isValid(pos)) {
             return -1;
         }
 
diff --git a/src/main/java/dan200/computercraft/shared/Peripherals.java b/src/main/java/dan200/computercraft/shared/Peripherals.java
index 3357d264b..9f7b9e179 100644
--- a/src/main/java/dan200/computercraft/shared/Peripherals.java
+++ b/src/main/java/dan200/computercraft/shared/Peripherals.java
@@ -35,13 +35,11 @@ public final class Peripherals {
 
     @Nullable
     public static IPeripheral getPeripheral(World world, BlockPos pos, Direction side) {
-        return World.method_24794(pos) && !world.isClient ? getPeripheralAt(world, pos, side) : null;
+        return World.isValid(pos) && !world.isClient ? getPeripheralAt(world, pos, side) : null;
     }
 
     @Nullable
     private static IPeripheral getPeripheralAt(World world, BlockPos pos, Direction side) {
-        BlockEntity block = world.getBlockEntity(pos);
-
         // Try the handlers in order:
         for (IPeripheralProvider peripheralProvider : providers) {
             try {
diff --git a/src/main/java/dan200/computercraft/shared/command/CommandUtils.java b/src/main/java/dan200/computercraft/shared/command/CommandUtils.java
index 26754058b..375dd4402 100644
--- a/src/main/java/dan200/computercraft/shared/command/CommandUtils.java
+++ b/src/main/java/dan200/computercraft/shared/command/CommandUtils.java
@@ -17,7 +17,7 @@ import com.mojang.brigadier.suggestion.SuggestionsBuilder;
 import dan200.computercraft.api.turtle.FakePlayer;
 
 import net.minecraft.entity.Entity;
-import net.minecraft.server.command.CommandSource;
+import net.minecraft.command.CommandSource;
 import net.minecraft.server.command.ServerCommandSource;
 import net.minecraft.server.network.ServerPlayerEntity;
 
diff --git a/src/main/java/dan200/computercraft/shared/computer/apis/CommandAPI.java b/src/main/java/dan200/computercraft/shared/computer/apis/CommandAPI.java
index fe87d15dd..fa7cf62cd 100644
--- a/src/main/java/dan200/computercraft/shared/computer/apis/CommandAPI.java
+++ b/src/main/java/dan200/computercraft/shared/computer/apis/CommandAPI.java
@@ -207,7 +207,7 @@ public class CommandAPI implements ILuaAPI {
         World world = this.computer.getWorld();
         BlockPos min = new BlockPos(Math.min(minX, maxX), Math.min(minY, maxY), Math.min(minZ, maxZ));
         BlockPos max = new BlockPos(Math.max(minX, maxX), Math.max(minY, maxY), Math.max(minZ, maxZ));
-        if (!World.method_24794(min) || !World.method_24794(max)) {
+        if (!World.isValid(min) || !World.isValid(max)) {
             throw new LuaException("Co-ordinates out of range");
         }
 
@@ -284,7 +284,7 @@ public class CommandAPI implements ILuaAPI {
         // Get the details of the block
         World world = this.computer.getWorld();
         BlockPos position = new BlockPos(x, y, z);
-        if (World.method_24794(position)) {
+        if (World.isValid(position)) {
             return getBlockInfo(world, position);
         } else {
             throw new LuaException("Co-ordinates out of range");
diff --git a/src/main/java/dan200/computercraft/shared/computer/core/ServerComputer.java b/src/main/java/dan200/computercraft/shared/computer/core/ServerComputer.java
index 770e78af8..cc4b1a7fa 100644
--- a/src/main/java/dan200/computercraft/shared/computer/core/ServerComputer.java
+++ b/src/main/java/dan200/computercraft/shared/computer/core/ServerComputer.java
@@ -316,7 +316,7 @@ public class ServerComputer extends ServerTerminal implements IComputer, IComput
     @Nonnull
     @Override
     public String getHostString() {
-        return String.format("ComputerCraft %s (Minecraft %s)", ComputerCraftAPI.getInstalledVersion(), "1.16.2");
+        return String.format("ComputerCraft %s (Minecraft %s)", ComputerCraftAPI.getInstalledVersion(), "1.16.4");
     }
 
     @Nonnull
diff --git a/src/main/java/dan200/computercraft/shared/turtle/core/TurtleMoveCommand.java b/src/main/java/dan200/computercraft/shared/turtle/core/TurtleMoveCommand.java
index 780e117b1..1e0bfde8c 100644
--- a/src/main/java/dan200/computercraft/shared/turtle/core/TurtleMoveCommand.java
+++ b/src/main/java/dan200/computercraft/shared/turtle/core/TurtleMoveCommand.java
@@ -119,10 +119,10 @@ public class TurtleMoveCommand implements ITurtleCommand {
     }
 
     private static TurtleCommandResult canEnter(TurtlePlayer turtlePlayer, World world, BlockPos position) {
-        if (World.isHeightInvalid(position)) {
+        if (World.isOutOfBuildLimitVertically(position)) {
             return TurtleCommandResult.failure(position.getY() < 0 ? "Too low to move" : "Too high to move");
         }
-        if (!World.method_24794(position)) {
+        if (!World.isValid(position)) {
             return TurtleCommandResult.failure("Cannot leave the world");
         }
 
diff --git a/src/main/java/dan200/computercraft/shared/turtle/core/TurtlePlaceCommand.java b/src/main/java/dan200/computercraft/shared/turtle/core/TurtlePlaceCommand.java
index e02ec415e..a21479d1c 100644
--- a/src/main/java/dan200/computercraft/shared/turtle/core/TurtlePlaceCommand.java
+++ b/src/main/java/dan200/computercraft/shared/turtle/core/TurtlePlaceCommand.java
@@ -364,7 +364,7 @@ public class TurtlePlaceCommand implements ITurtleCommand {
     private static boolean canDeployOnBlock(@Nonnull ItemPlacementContext context, ITurtleAccess turtle, TurtlePlayer player, BlockPos position,
                                             Direction side, boolean allowReplaceable, String[] outErrorMessage) {
         World world = turtle.getWorld();
-        if (!World.method_24794(position) || world.isAir(position) || (context.getStack()
+        if (!World.isValid(position) || world.isAir(position) || (context.getStack()
                                                                               .getItem() instanceof BlockItem && WorldUtil.isLiquidBlock(world,
                                                                                                                                          position))) {
             return false;
diff --git a/src/main/java/dan200/computercraft/shared/turtle/core/TurtlePlayer.java b/src/main/java/dan200/computercraft/shared/turtle/core/TurtlePlayer.java
index 35150d795..724898819 100644
--- a/src/main/java/dan200/computercraft/shared/turtle/core/TurtlePlayer.java
+++ b/src/main/java/dan200/computercraft/shared/turtle/core/TurtlePlayer.java
@@ -77,7 +77,7 @@ public final class TurtlePlayer extends FakePlayer {
     private void setState(ITurtleAccess turtle) {
         if (this.currentScreenHandler != playerScreenHandler) {
             ComputerCraft.log.warn("Turtle has open container ({})", this.currentScreenHandler);
-            closeCurrentScreen();
+            closeHandledScreen();
         }
 
         BlockPos position = turtle.getPosition();
@@ -91,13 +91,8 @@ public final class TurtlePlayer extends FakePlayer {
     }
 
     public static TurtlePlayer get(ITurtleAccess access) {
-         ServerWorld world = (ServerWorld) access.getWorld();
         if( !(access instanceof TurtleBrain) ) return create( access );
 
-         /*if (!(access instanceof TurtleBrain)) {
-            return new TurtlePlayer(world, access.getOwningPlayer());
-        }*/
-
         TurtleBrain brain = (TurtleBrain) access;
         TurtlePlayer player = brain.m_cachedPlayer;
         if (player == null || player.getGameProfile() != getProfile(access.getOwningPlayer()) || player.getEntityWorld() != access.getWorld()) {
diff --git a/src/main/java/dan200/computercraft/shared/util/FakeNetHandler.java b/src/main/java/dan200/computercraft/shared/util/FakeNetHandler.java
index cd5d9d8b6..3b0b93d99 100644
--- a/src/main/java/dan200/computercraft/shared/util/FakeNetHandler.java
+++ b/src/main/java/dan200/computercraft/shared/util/FakeNetHandler.java
@@ -14,7 +14,6 @@ import dan200.computercraft.api.turtle.FakePlayer;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.util.concurrent.Future;
 import io.netty.util.concurrent.GenericFutureListener;
-
 import net.minecraft.network.ClientConnection;
 import net.minecraft.network.NetworkSide;
 import net.minecraft.network.NetworkState;
@@ -25,15 +24,12 @@ import net.minecraft.network.packet.c2s.play.BoatPaddleStateC2SPacket;
 import net.minecraft.network.packet.c2s.play.BookUpdateC2SPacket;
 import net.minecraft.network.packet.c2s.play.ButtonClickC2SPacket;
 import net.minecraft.network.packet.c2s.play.ChatMessageC2SPacket;
-import net.minecraft.network.packet.c2s.play.ClickWindowC2SPacket;
 import net.minecraft.network.packet.c2s.play.ClientCommandC2SPacket;
 import net.minecraft.network.packet.c2s.play.ClientSettingsC2SPacket;
 import net.minecraft.network.packet.c2s.play.ClientStatusC2SPacket;
-import net.minecraft.network.packet.c2s.play.ConfirmGuiActionC2SPacket;
 import net.minecraft.network.packet.c2s.play.CraftRequestC2SPacket;
 import net.minecraft.network.packet.c2s.play.CreativeInventoryActionC2SPacket;
 import net.minecraft.network.packet.c2s.play.CustomPayloadC2SPacket;
-import net.minecraft.network.packet.c2s.play.GuiCloseC2SPacket;
 import net.minecraft.network.packet.c2s.play.HandSwingC2SPacket;
 import net.minecraft.network.packet.c2s.play.KeepAliveC2SPacket;
 import net.minecraft.network.packet.c2s.play.PickFromInventoryC2SPacket;
@@ -48,7 +44,6 @@ import net.minecraft.network.packet.c2s.play.QueryEntityNbtC2SPacket;
 import net.minecraft.network.packet.c2s.play.RenameItemC2SPacket;
 import net.minecraft.network.packet.c2s.play.RequestCommandCompletionsC2SPacket;
 import net.minecraft.network.packet.c2s.play.ResourcePackStatusC2SPacket;
-import net.minecraft.network.packet.c2s.play.SelectVillagerTradeC2SPacket;
 import net.minecraft.network.packet.c2s.play.SpectatorTeleportC2SPacket;
 import net.minecraft.network.packet.c2s.play.TeleportConfirmC2SPacket;
 import net.minecraft.network.packet.c2s.play.UpdateBeaconC2SPacket;
@@ -127,10 +122,6 @@ public class FakeNetHandler extends ServerPlayNetworkHandler {
     public void onJigsawUpdate(@Nonnull UpdateJigsawC2SPacket packet) {
     }
 
-    @Override
-    public void onVillagerTradeSelect(@Nonnull SelectVillagerTradeC2SPacket packet) {
-    }
-
     @Override
     public void onBookUpdate(@Nonnull BookUpdateC2SPacket packet) {
     }
@@ -207,14 +198,6 @@ public class FakeNetHandler extends ServerPlayNetworkHandler {
     public void onClientStatus(@Nonnull ClientStatusC2SPacket packet) {
     }
 
-    @Override
-    public void onGuiClose(@Nonnull GuiCloseC2SPacket packet) {
-    }
-
-    @Override
-    public void onClickWindow(@Nonnull ClickWindowC2SPacket packet) {
-    }
-
     @Override
     public void onCraftRequest(@Nonnull CraftRequestC2SPacket packet) {
     }
@@ -227,10 +210,6 @@ public class FakeNetHandler extends ServerPlayNetworkHandler {
     public void onCreativeInventoryAction(@Nonnull CreativeInventoryActionC2SPacket packet) {
     }
 
-    @Override
-    public void onConfirmTransaction(@Nonnull ConfirmGuiActionC2SPacket packet) {
-    }
-
     @Override
     public void onSignUpdate(@Nonnull UpdateSignC2SPacket packet) {
     }
@@ -309,10 +288,6 @@ public class FakeNetHandler extends ServerPlayNetworkHandler {
             this.closeReason = message;
         }
 
-        @Override
-        public void setupEncryption(@Nonnull SecretKey key) {
-        }
-
         @Nonnull
         @Override
         public PacketListener getPacketListener() {
diff --git a/src/main/java/dan200/computercraft/shared/util/WorldUtil.java b/src/main/java/dan200/computercraft/shared/util/WorldUtil.java
index 284af67d3..df99b66d1 100644
--- a/src/main/java/dan200/computercraft/shared/util/WorldUtil.java
+++ b/src/main/java/dan200/computercraft/shared/util/WorldUtil.java
@@ -40,7 +40,7 @@ public final class WorldUtil {
                                                                         .makeMap();
 
     public static boolean isLiquidBlock(World world, BlockPos pos) {
-        if (!World.method_24794(pos)) {
+        if (!World.isValid(pos)) {
             return false;
         }
         return world.getBlockState(pos)