diff --git a/src/main/java/net/minestom/server/advancements/Advancement.java b/src/main/java/net/minestom/server/advancements/Advancement.java
index a2c9321c1..c21a87e49 100644
--- a/src/main/java/net/minestom/server/advancements/Advancement.java
+++ b/src/main/java/net/minestom/server/advancements/Advancement.java
@@ -294,8 +294,7 @@ public class Advancement {
 
             final Advancement parent = getParent();
             if (parent != null) {
-                final String parentIdentifier = parent.getIdentifier();
-                adv.parentIdentifier = parentIdentifier;
+                adv.parentIdentifier = parent.getIdentifier();
             }
 
             adv.displayData = toDisplayData();
diff --git a/src/main/java/net/minestom/server/chat/ChatParser.java b/src/main/java/net/minestom/server/chat/ChatParser.java
index 388ef083e..181fd2668 100644
--- a/src/main/java/net/minestom/server/chat/ChatParser.java
+++ b/src/main/java/net/minestom/server/chat/ChatParser.java
@@ -58,7 +58,7 @@ public class ChatParser {
             String colorString = textObject.get("color").getAsString();
             if (colorString.startsWith("#")) {
                 // RGB format
-                builder.append("{" + colorString + "}");
+                builder.append("{").append(colorString).append("}");
             } else {
                 // Color simple name
                 ChatColor color = ChatColor.fromName(colorString);
diff --git a/src/main/java/net/minestom/server/command/CommandManager.java b/src/main/java/net/minestom/server/command/CommandManager.java
index edd174d59..7333e5c91 100644
--- a/src/main/java/net/minestom/server/command/CommandManager.java
+++ b/src/main/java/net/minestom/server/command/CommandManager.java
@@ -203,9 +203,7 @@ public class CommandManager {
 
             List<String> names = new ArrayList<>();
             names.add(command.getName());
-            for (String alias : command.getAliases()) {
-                names.add(alias);
-            }
+            names.addAll(Arrays.asList(command.getAliases()));
             for (String name : names) {
                 createCommand(nodes, cmdChildren, name, syntaxes, rootChildren);
             }
diff --git a/src/main/java/net/minestom/server/inventory/type/AnvilInventory.java b/src/main/java/net/minestom/server/inventory/type/AnvilInventory.java
index 7ef7f2aae..d66a5135c 100644
--- a/src/main/java/net/minestom/server/inventory/type/AnvilInventory.java
+++ b/src/main/java/net/minestom/server/inventory/type/AnvilInventory.java
@@ -27,7 +27,7 @@ public class AnvilInventory extends Inventory {
      * @param cost the new anvil repair cost
      */
     public void setRepairCost(short cost) {
-        this.repairCost = repairCost;
+        this.repairCost = cost;
         sendProperty(InventoryProperty.ANVIL_REPAIR_COST, cost);
     }
 }
diff --git a/src/main/java/net/minestom/server/timer/Task.java b/src/main/java/net/minestom/server/timer/Task.java
index b1a48e26b..fa1ba5724 100644
--- a/src/main/java/net/minestom/server/timer/Task.java
+++ b/src/main/java/net/minestom/server/timer/Task.java
@@ -54,13 +54,11 @@ public class Task implements Runnable {
             try {
                 this.runnable.run();
             } catch (Exception e) {
-                System.err.println(
-                        String.format(
-                                "An exception in %s task %s is occurred! (%s)",
-                                this.shutdown ? "shutdown" : "",
-                                this.id,
-                                e.getMessage()
-                        )
+                System.err.printf(
+                        "An exception in %s task %s is occurred! (%s)%n",
+                        this.shutdown ? "shutdown" : "",
+                        this.id,
+                        e.getMessage()
                 );
                 e.printStackTrace();
             } finally {
diff --git a/src/main/java/net/minestom/server/utils/chunk/ChunkUtils.java b/src/main/java/net/minestom/server/utils/chunk/ChunkUtils.java
index fff03bc9a..9e4f4c02e 100644
--- a/src/main/java/net/minestom/server/utils/chunk/ChunkUtils.java
+++ b/src/main/java/net/minestom/server/utils/chunk/ChunkUtils.java
@@ -124,7 +124,8 @@ public final class ChunkUtils {
     public static int[] indexToPosition(int index, int chunkX, int chunkZ) {
         int z = (byte) (index >> 12 & 0xF);
         final int y = (index >>> 4 & 0xFF);
-        int x = (byte) (index >> 0 & 0xF);
+        // index >> 0 = index
+        int x = (byte) (index & 0xF);
 
         x += 16 * chunkX;
         z += 16 * chunkZ;