diff --git a/src/main/java/fr/themode/minestom/Main.java b/src/main/java/fr/themode/minestom/Main.java
index d7a97c89d..6e4e3386a 100644
--- a/src/main/java/fr/themode/minestom/Main.java
+++ b/src/main/java/fr/themode/minestom/Main.java
@@ -39,7 +39,7 @@ public class Main {
         blockManager = new BlockManager();
         entityManager = new EntityManager();
 
-        blockManager.registerBlock("stone", StoneBlock::new);
+        blockManager.registerBlock(StoneBlock::new);
 
         server = new TCPServer(new MinecraftProtocol()).addHandler(new ServerHandler() {
             @Override
diff --git a/src/main/java/fr/themode/minestom/instance/BlockManager.java b/src/main/java/fr/themode/minestom/instance/BlockManager.java
index 07b30ab7e..acf460a0c 100644
--- a/src/main/java/fr/themode/minestom/instance/BlockManager.java
+++ b/src/main/java/fr/themode/minestom/instance/BlockManager.java
@@ -6,14 +6,23 @@ import java.util.function.Supplier;
 
 public class BlockManager {
 
-    private Map<String, CustomBlock> blocks = new HashMap<>();
+    private Map<Integer, CustomBlock> blocksInternalId = new HashMap<>();
+    private Map<String, CustomBlock> blocksId = new HashMap<>();
 
-    public void registerBlock(String id, Supplier<CustomBlock> blocks) {
-        this.blocks.put(id, blocks.get());
+    public void registerBlock(Supplier<CustomBlock> blocks) {
+        CustomBlock customBlock = blocks.get();
+        String identifier = customBlock.getIdentifier();
+        int id = customBlock.getId();
+        this.blocksInternalId.put(id, customBlock);
+        this.blocksId.put(identifier, customBlock);
     }
 
-    public CustomBlock getBlock(String id) {
-        return this.blocks.get(id);
+    public CustomBlock getBlock(String identifier) {
+        return blocksId.get(identifier);
+    }
+
+    public CustomBlock getBlock(int id) {
+        return blocksInternalId.get(id);
     }
 
 }
diff --git a/src/main/java/fr/themode/minestom/instance/Chunk.java b/src/main/java/fr/themode/minestom/instance/Chunk.java
index 5df4493ec..5066ec1f9 100644
--- a/src/main/java/fr/themode/minestom/instance/Chunk.java
+++ b/src/main/java/fr/themode/minestom/instance/Chunk.java
@@ -18,7 +18,7 @@ public class Chunk {
     private int chunkX, chunkZ;
     private Biome biome;
     private short[] blocksId = new short[CHUNK_SIZE];
-    private String[] customBlocks = new String[CHUNK_SIZE];
+    private int[] customBlocks = new int[CHUNK_SIZE];
 
     public Chunk(Biome biome, int chunkX, int chunkZ) {
         this.biome = biome;
@@ -30,23 +30,27 @@ public class Chunk {
         int index = getIndex(x, y, z);
         this.blocksId[index] = blockId;
         if (blockId == 0) {
-            this.customBlocks[index] = null;
+            this.customBlocks[index] = 0;
         }
     }
 
     protected void setBlock(byte x, byte y, byte z, String blockId) {
-        int index = getIndex(x, y, z);
         CustomBlock customBlock = Main.getBlockManager().getBlock(blockId);
+        if (customBlock == null)
+            throw new IllegalArgumentException("The block " + blockId + " does not exist or isn't registered");
+
+        int index = getIndex(x, y, z);
         this.blocksId[index] = customBlock.getType();
-        this.customBlocks[index] = blockId;
+        this.customBlocks[index] = customBlock.getId();
     }
 
     public short getBlockId(byte x, byte y, byte z) {
         return this.blocksId[getIndex(x, y, z)];
     }
 
-    public String getCustomBlockId(byte x, byte y, byte z) {
-        return this.customBlocks[getIndex(x, y, z)];
+    public CustomBlock getCustomBlock(byte x, byte y, byte z) {
+        int id = this.customBlocks[getIndex(x, y, z)];
+        return id != 0 ? Main.getBlockManager().getBlock(id) : null;
     }
 
     public void addEntity(Entity entity) {
diff --git a/src/main/java/fr/themode/minestom/instance/CustomBlock.java b/src/main/java/fr/themode/minestom/instance/CustomBlock.java
index b8cf21000..eaf2f7a94 100644
--- a/src/main/java/fr/themode/minestom/instance/CustomBlock.java
+++ b/src/main/java/fr/themode/minestom/instance/CustomBlock.java
@@ -2,20 +2,28 @@ package fr.themode.minestom.instance;
 
 import fr.themode.minestom.entity.Player;
 
+import java.util.concurrent.atomic.AtomicInteger;
+
 public abstract class CustomBlock {
 
-    private short type;
+    private static final AtomicInteger idCounter = new AtomicInteger();
 
-    public CustomBlock(short type) {
-        this.type = type;
+    private int id;
+
+    public CustomBlock() {
+        this.id = idCounter.incrementAndGet();
     }
 
+    public abstract short getType();
+
+    public abstract String getIdentifier();
+
     /*
       Time in ms
      */
     public abstract int getBreakDelay(Player player);
 
-    public short getType() {
-        return type;
+    public int getId() {
+        return id;
     }
 }
diff --git a/src/main/java/fr/themode/minestom/instance/Instance.java b/src/main/java/fr/themode/minestom/instance/Instance.java
index 733c7dc89..4fae0e7dd 100644
--- a/src/main/java/fr/themode/minestom/instance/Instance.java
+++ b/src/main/java/fr/themode/minestom/instance/Instance.java
@@ -19,7 +19,7 @@ public class Instance {
     private GroupedCollections<EntityCreature> creatures = new GroupedCollections<>(new CopyOnWriteArrayList());
     private GroupedCollections<Player> players = new GroupedCollections<>(new CopyOnWriteArrayList());
 
-    private Set<Chunk> chunksSet = new CopyOnWriteArraySet<>();
+    private Set<Chunk> chunksSet = new CopyOnWriteArraySet<>(); // TODO change for a map with position as key and chunk as value
 
     public Instance(UUID uniqueId) {
         this.uniqueId = uniqueId;
@@ -46,9 +46,9 @@ public class Instance {
         return chunk.getBlockId((byte) (x % 16), (byte) y, (byte) (z % 16));
     }
 
-    public String getCustomBlockId(int x, int y, int z) {
+    public CustomBlock getCustomBlock(int x, int y, int z) {
         Chunk chunk = getChunkAt(x, z);
-        return chunk.getCustomBlockId((byte) (x % 16), (byte) y, (byte) (z % 16));
+        return chunk.getCustomBlock((byte) (x % 16), (byte) y, (byte) (z % 16));
     }
 
     public BlockBatch createBlockBatch() {
diff --git a/src/main/java/fr/themode/minestom/instance/demo/StoneBlock.java b/src/main/java/fr/themode/minestom/instance/demo/StoneBlock.java
index 4aab1a8e1..3a047ad52 100644
--- a/src/main/java/fr/themode/minestom/instance/demo/StoneBlock.java
+++ b/src/main/java/fr/themode/minestom/instance/demo/StoneBlock.java
@@ -5,12 +5,18 @@ import fr.themode.minestom.instance.CustomBlock;
 
 public class StoneBlock extends CustomBlock {
 
-    public StoneBlock() {
-        super((short) 1);
+    @Override
+    public short getType() {
+        return 1;
+    }
+
+    @Override
+    public String getIdentifier() {
+        return "stone_block";
     }
 
     @Override
     public int getBreakDelay(Player player) {
         return 750;
     }
-}
+}
\ No newline at end of file
diff --git a/src/main/java/fr/themode/minestom/net/packet/client/play/ClientPlayerBlockPlacementPacket.java b/src/main/java/fr/themode/minestom/net/packet/client/play/ClientPlayerBlockPlacementPacket.java
index 9d657c84e..597b45b2a 100644
--- a/src/main/java/fr/themode/minestom/net/packet/client/play/ClientPlayerBlockPlacementPacket.java
+++ b/src/main/java/fr/themode/minestom/net/packet/client/play/ClientPlayerBlockPlacementPacket.java
@@ -25,7 +25,7 @@ public class ClientPlayerBlockPlacementPacket implements ClientPlayPacket {
         int offsetY = blockFace == ClientPlayerDiggingPacket.BlockFace.BOTTOM ? -1 : blockFace == ClientPlayerDiggingPacket.BlockFace.TOP ? 1 : 0;
         int offsetZ = blockFace == ClientPlayerDiggingPacket.BlockFace.NORTH ? -1 : blockFace == ClientPlayerDiggingPacket.BlockFace.SOUTH ? 1 : 0;
 
-        instance.setBlock(position.getX() + offsetX, position.getY() + offsetY, position.getZ() + offsetZ, "stone");
+        instance.setBlock(position.getX() + offsetX, position.getY() + offsetY, position.getZ() + offsetZ, "stone_block");
         player.getInventory().refreshSlot(player.getHeldSlot());
         // TODO consume block in hand for survival players
         /*Random random = new Random();
diff --git a/src/main/java/fr/themode/minestom/net/packet/client/play/ClientPlayerDiggingPacket.java b/src/main/java/fr/themode/minestom/net/packet/client/play/ClientPlayerDiggingPacket.java
index ab817efb6..5186e6558 100644
--- a/src/main/java/fr/themode/minestom/net/packet/client/play/ClientPlayerDiggingPacket.java
+++ b/src/main/java/fr/themode/minestom/net/packet/client/play/ClientPlayerDiggingPacket.java
@@ -1,7 +1,6 @@
 package fr.themode.minestom.net.packet.client.play;
 
 import fr.adamaq01.ozao.net.Buffer;
-import fr.themode.minestom.Main;
 import fr.themode.minestom.entity.GameMode;
 import fr.themode.minestom.entity.Player;
 import fr.themode.minestom.instance.CustomBlock;
@@ -30,9 +29,8 @@ public class ClientPlayerDiggingPacket implements ClientPlayPacket {
                 } else if (player.getGameMode() == GameMode.SURVIVAL) {
                     Instance instance = player.getInstance();
                     if (instance != null) {
-                        String customBlockId = instance.getCustomBlockId(position.getX(), position.getY(), position.getZ());
-                        if (customBlockId != null) {
-                            CustomBlock customBlock = Main.getBlockManager().getBlock(customBlockId);
+                        CustomBlock customBlock = instance.getCustomBlock(position.getX(), position.getY(), position.getZ());
+                        if (customBlock != null) {
                             player.refreshTargetBlock(customBlock, position);
                             addEffect(player);
                         } else {