diff --git a/api/src/main/java/com/github/retrooper/packetevents/manager/server/SystemOS.java b/api/src/main/java/com/github/retrooper/packetevents/manager/server/SystemOS.java
index 8fb781e91..db72bb22d 100644
--- a/api/src/main/java/com/github/retrooper/packetevents/manager/server/SystemOS.java
+++ b/api/src/main/java/com/github/retrooper/packetevents/manager/server/SystemOS.java
@@ -18,6 +18,8 @@
 
 package com.github.retrooper.packetevents.manager.server;
 
+import java.util.Locale;
+
 /**
  * System Operating system.
  *
@@ -36,9 +38,9 @@ public enum SystemOS {
      * @return Operating System.
      */
     public static SystemOS getOSNoCache() {
-        final String os = System.getProperty("os.name").toLowerCase();
+        final String os = System.getProperty("os.name").toLowerCase(Locale.ROOT);
         for (SystemOS sysos : values()) {
-            if (os.contains(sysos.name().toLowerCase())) {
+            if (os.contains(sysos.name().toLowerCase(Locale.ROOT))) {
                 return sysos;
             }
         }
diff --git a/api/src/main/java/com/github/retrooper/packetevents/protocol/item/type/ItemTypes.java b/api/src/main/java/com/github/retrooper/packetevents/protocol/item/type/ItemTypes.java
index cdd017dc8..7e9cbd5e6 100644
--- a/api/src/main/java/com/github/retrooper/packetevents/protocol/item/type/ItemTypes.java
+++ b/api/src/main/java/com/github/retrooper/packetevents/protocol/item/type/ItemTypes.java
@@ -43,6 +43,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
@@ -2074,7 +2075,7 @@ public final class ItemTypes {
     }
 
     public static Builder builder(String key) {
-        return new Builder(key.toLowerCase());
+        return new Builder(key.toLowerCase(Locale.ROOT));
     }
 
     @ApiStatus.Internal
diff --git a/api/src/main/java/com/github/retrooper/packetevents/wrapper/play/server/WrapperPlayServerScoreboardObjective.java b/api/src/main/java/com/github/retrooper/packetevents/wrapper/play/server/WrapperPlayServerScoreboardObjective.java
index c3c5c3238..d211bcf5d 100644
--- a/api/src/main/java/com/github/retrooper/packetevents/wrapper/play/server/WrapperPlayServerScoreboardObjective.java
+++ b/api/src/main/java/com/github/retrooper/packetevents/wrapper/play/server/WrapperPlayServerScoreboardObjective.java
@@ -23,11 +23,12 @@ import com.github.retrooper.packetevents.manager.server.ServerVersion;
 import com.github.retrooper.packetevents.protocol.packettype.PacketType;
 import com.github.retrooper.packetevents.protocol.score.ScoreFormat;
 import com.github.retrooper.packetevents.util.LegacyFormat;
-import com.github.retrooper.packetevents.util.adventure.AdventureSerializer;
 import com.github.retrooper.packetevents.wrapper.PacketWrapper;
 import net.kyori.adventure.text.Component;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Locale;
+
 public class WrapperPlayServerScoreboardObjective extends PacketWrapper<WrapperPlayServerScoreboardObjective> {
 
     private String name;
@@ -96,9 +97,9 @@ public class WrapperPlayServerScoreboardObjective extends PacketWrapper<WrapperP
                 String legacyText = this.getSerializers().asLegacy(this.displayName);
                 writeString(LegacyFormat.trimLegacyFormat(legacyText, 32));
                 if (renderType != null) {
-                    writeString(renderType.name().toLowerCase());
+                    writeString(renderType.name().toLowerCase(Locale.ROOT));
                 } else {
-                    writeString(RenderType.INTEGER.name().toLowerCase());
+                    writeString(RenderType.INTEGER.name().toLowerCase(Locale.ROOT));
                 }
             } else {
                 writeComponent(displayName);
diff --git a/api/src/test/java/com/github/retrooper/packetevents/test/base/TestPacketEventsBuilder.java b/api/src/test/java/com/github/retrooper/packetevents/test/base/TestPacketEventsBuilder.java
index d12068188..d39fa121d 100644
--- a/api/src/test/java/com/github/retrooper/packetevents/test/base/TestPacketEventsBuilder.java
+++ b/api/src/test/java/com/github/retrooper/packetevents/test/base/TestPacketEventsBuilder.java
@@ -22,6 +22,7 @@ import org.jetbrains.annotations.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.util.Locale;
 import java.util.logging.Level;
 
 public class TestPacketEventsBuilder {
@@ -85,7 +86,7 @@ public class TestPacketEventsBuilder {
             public void load() {
                 if (!loaded) {
                     //Resolve server version and cache
-                    String id = plugin.getName().toLowerCase();
+                    String id = plugin.getName().toLowerCase(Locale.ROOT);
                     PacketEvents.IDENTIFIER = "pe-" + id;
                     PacketEvents.ENCODER_NAME = "pe-encoder-" + id;
                     PacketEvents.DECODER_NAME = "pe-decoder-" + id;
diff --git a/netty-common/src/main/java/io/github/retrooper/packetevents/impl/netty/factory/NettyPacketEventsBuilder.java b/netty-common/src/main/java/io/github/retrooper/packetevents/impl/netty/factory/NettyPacketEventsBuilder.java
index ce928e318..7845ee2cf 100644
--- a/netty-common/src/main/java/io/github/retrooper/packetevents/impl/netty/factory/NettyPacketEventsBuilder.java
+++ b/netty-common/src/main/java/io/github/retrooper/packetevents/impl/netty/factory/NettyPacketEventsBuilder.java
@@ -33,6 +33,8 @@ import io.github.retrooper.packetevents.impl.netty.NettyManagerImpl;
 import io.github.retrooper.packetevents.impl.netty.manager.player.PlayerManagerAbstract;
 import io.github.retrooper.packetevents.impl.netty.manager.server.ServerManagerAbstract;
 
+import java.util.Locale;
+
 public class NettyPacketEventsBuilder {
     private static PacketEventsAPI<BuildData> INSTANCE;
 
@@ -86,12 +88,13 @@ public class NettyPacketEventsBuilder {
             public void load() {
                 if (!loaded) {
                     //Resolve server version and cache
-                    PacketEvents.IDENTIFIER = "pe-" + data.getName().toLowerCase();
-                    PacketEvents.ENCODER_NAME = "pe-encoder-" + data.getName().toLowerCase();
-                    PacketEvents.DECODER_NAME = "pe-decoder-" + data.getName().toLowerCase();
-                    PacketEvents.CONNECTION_HANDLER_NAME = "pe-connection-handler-" + data.getName().toLowerCase();
-                    PacketEvents.SERVER_CHANNEL_HANDLER_NAME = "pe-connection-initializer-" + data.getName().toLowerCase();
-                    PacketEvents.TIMEOUT_HANDLER_NAME = "pe-timeout-handler-" + data.getName().toLowerCase();
+                    String id = data.getName().toLowerCase(Locale.ROOT);
+                    PacketEvents.IDENTIFIER = "pe-" + id;
+                    PacketEvents.ENCODER_NAME = "pe-encoder-" + id;
+                    PacketEvents.DECODER_NAME = "pe-decoder-" + id;
+                    PacketEvents.CONNECTION_HANDLER_NAME = "pe-connection-handler-" + id;
+                    PacketEvents.SERVER_CHANNEL_HANDLER_NAME = "pe-connection-initializer-" + id;
+                    PacketEvents.TIMEOUT_HANDLER_NAME = "pe-timeout-handler-" + id;
                     injector.inject();
 
                     loaded = true;
diff --git a/spigot/src/main/java/io/github/retrooper/packetevents/factory/spigot/SpigotPacketEventsBuilder.java b/spigot/src/main/java/io/github/retrooper/packetevents/factory/spigot/SpigotPacketEventsBuilder.java
index ba9004217..8743d88c4 100644
--- a/spigot/src/main/java/io/github/retrooper/packetevents/factory/spigot/SpigotPacketEventsBuilder.java
+++ b/spigot/src/main/java/io/github/retrooper/packetevents/factory/spigot/SpigotPacketEventsBuilder.java
@@ -57,6 +57,7 @@ import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
 import org.bukkit.plugin.Plugin;
 
+import java.util.Locale;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.BiConsumer;
 
@@ -103,7 +104,7 @@ public class SpigotPacketEventsBuilder {
             public void load() {
                 if (!loaded) {
                     //Resolve server version and cache
-                    String id = plugin.getName().toLowerCase();
+                    String id = plugin.getName().toLowerCase(Locale.ROOT);
                     PacketEvents.IDENTIFIER = "pe-" + id;
                     PacketEvents.ENCODER_NAME = "pe-encoder-" + id;
                     PacketEvents.DECODER_NAME = "pe-decoder-" + id;
diff --git a/sponge/src/main/java/io/github/retrooper/packetevents/sponge/factory/SpongePacketEventsBuilder.java b/sponge/src/main/java/io/github/retrooper/packetevents/sponge/factory/SpongePacketEventsBuilder.java
index 4b2bb6e11..bd302d5ea 100644
--- a/sponge/src/main/java/io/github/retrooper/packetevents/sponge/factory/SpongePacketEventsBuilder.java
+++ b/sponge/src/main/java/io/github/retrooper/packetevents/sponge/factory/SpongePacketEventsBuilder.java
@@ -46,6 +46,8 @@ import org.spongepowered.api.Sponge;
 import org.spongepowered.api.scheduler.Task;
 import org.spongepowered.plugin.PluginContainer;
 
+import java.util.Locale;
+
 public class SpongePacketEventsBuilder {
 
     private static PacketEventsAPI<PluginContainer> API_INSTANCE;
@@ -91,7 +93,7 @@ public class SpongePacketEventsBuilder {
                 if (loaded) return;
 
                 //Resolve server version and cache
-                String id = plugin.metadata().id().toLowerCase();
+                String id = plugin.metadata().id().toLowerCase(Locale.ROOT);
                 PacketEvents.IDENTIFIER = "pe-" + id;
                 PacketEvents.ENCODER_NAME = "pe-encoder-" + id;
                 PacketEvents.DECODER_NAME = "pe-decoder-" + id;