diff --git a/src/main/java/com/Acrobot/Breeze/Configuration/Configuration.java b/src/main/java/com/Acrobot/Breeze/Configuration/Configuration.java
index e62be3b9..86127e82 100644
--- a/src/main/java/com/Acrobot/Breeze/Configuration/Configuration.java
+++ b/src/main/java/com/Acrobot/Breeze/Configuration/Configuration.java
@@ -8,6 +8,7 @@ import java.io.IOException;
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Scanner;
 
@@ -30,7 +31,7 @@ public class Configuration {
         @Override
         public <T> Object parseToJava(Class<T> type, Object object) {
             if (object instanceof String && type.isEnum()) {
-                return Enum.valueOf((Class<? extends Enum>) type, ((String) object).toUpperCase());
+                return Enum.valueOf((Class<? extends Enum>) type, ((String) object).toUpperCase(Locale.ROOT));
             }
             return object;
         }
@@ -62,8 +63,8 @@ public class Configuration {
                 try {
                     if (config.isSet(path)) {
                         field.set(null, getParser(field).parseToJava(field.getType(), config.get(path)));
-                    } else if (config.isSet(path.toLowerCase())) {
-                        field.set(null, getParser(field).parseToJava(field.getType(), config.get(path.toLowerCase())));
+                    } else if (config.isSet(path.toLowerCase(Locale.ROOT))) {
+                        field.set(null, getParser(field).parseToJava(field.getType(), config.get(path.toLowerCase(Locale.ROOT))));
                     } else {
                         if (field.isAnnotationPresent(PrecededBySpace.class)) {
                             writer.newLine();
@@ -131,7 +132,7 @@ public class Configuration {
      * @param valueParser The parser itself
      */
     public static void registerParser(String name, ValueParser valueParser) {
-        parsers.put(name.toLowerCase(), valueParser);
+        parsers.put(name.toLowerCase(Locale.ROOT), valueParser);
     }
 
     /**
@@ -140,7 +141,7 @@ public class Configuration {
      * @return The parser or null if it doesn't exist
      */
     public static ValueParser getParser(String name) {
-        return parsers.get(name.toLowerCase());
+        return parsers.get(name.toLowerCase(Locale.ROOT));
     }
 
     /**
diff --git a/src/main/java/com/Acrobot/Breeze/Utils/MaterialUtil.java b/src/main/java/com/Acrobot/Breeze/Utils/MaterialUtil.java
index c0f664b6..ee6801e9 100644
--- a/src/main/java/com/Acrobot/Breeze/Utils/MaterialUtil.java
+++ b/src/main/java/com/Acrobot/Breeze/Utils/MaterialUtil.java
@@ -26,6 +26,7 @@ import org.yaml.snakeyaml.nodes.Tag;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.logging.Level;
 import java.util.regex.Matcher;
@@ -127,7 +128,7 @@ public class MaterialUtil {
      * @return Material found
      */
     public static Material getMaterial(String name) {
-        String formatted = name.replaceAll("([a-z])([A-Z1-9])", "$1_$2").replace(' ', '_').toUpperCase();
+        String formatted = name.replaceAll("([a-z])([A-Z1-9])", "$1_$2").replace(' ', '_').toUpperCase(Locale.ROOT);
 
         Material material = MATERIAL_CACHE.get(formatted);
         if (material != null) {
@@ -394,10 +395,10 @@ public class MaterialUtil {
     private static class EnumParser<E extends Enum<E>> {
         private E parse(String name, E[] values) {
             try {
-                return E.valueOf(values[0].getDeclaringClass(), name.toUpperCase());
+                return E.valueOf(values[0].getDeclaringClass(), name.toUpperCase(Locale.ROOT));
             } catch (IllegalArgumentException exception) {
                 E currentEnum = null;
-                String[] typeParts = name.replaceAll("([a-z])([A-Z1-9])", "$1_$2").toUpperCase().split("[ _]");
+                String[] typeParts = name.replaceAll("([a-z])([A-Z1-9])", "$1_$2").toUpperCase(Locale.ROOT).split("[ _]");
                 int length = Short.MAX_VALUE;
                 for (E e : values) {
                     String enumName = e.name();
diff --git a/src/main/java/com/Acrobot/Breeze/Utils/PriceUtil.java b/src/main/java/com/Acrobot/Breeze/Utils/PriceUtil.java
index 06be8d9d..f4601b9e 100644
--- a/src/main/java/com/Acrobot/Breeze/Utils/PriceUtil.java
+++ b/src/main/java/com/Acrobot/Breeze/Utils/PriceUtil.java
@@ -1,6 +1,7 @@
 package com.Acrobot.Breeze.Utils;
 
 import java.math.BigDecimal;
+import java.util.Locale;
 
 /**
  * @author Acrobot
@@ -23,8 +24,8 @@ public class PriceUtil {
      * @return exact price
      */
     public static BigDecimal getExact(String text, char indicator) {
-        String[] split = text.replace(" ", "").toLowerCase().split(":");
-        String character = String.valueOf(indicator).toLowerCase();
+        String[] split = text.replace(" ", "").toLowerCase(Locale.ROOT).split(":");
+        String character = String.valueOf(indicator).toLowerCase(Locale.ROOT);
 
         for (String part : split) {
             if (!part.startsWith(character) && !part.endsWith(character)) {
diff --git a/src/main/java/com/Acrobot/Breeze/Utils/StringUtil.java b/src/main/java/com/Acrobot/Breeze/Utils/StringUtil.java
index eeeaef81..302a5154 100644
--- a/src/main/java/com/Acrobot/Breeze/Utils/StringUtil.java
+++ b/src/main/java/com/Acrobot/Breeze/Utils/StringUtil.java
@@ -4,6 +4,7 @@ import org.apache.commons.lang.WordUtils;
 import org.bukkit.ChatColor;
 
 import java.util.Collection;
+import java.util.Locale;
 
 /**
  * @author Acrobot
@@ -18,9 +19,12 @@ public class StringUtil {
      * @return Reformatted string
      */
     public static String capitalizeFirstLetter(String string, char separator) {
+        if (string == null || string.isEmpty()) {
+            return string;
+        }
         char[] separators = new char[]{separator};
 
-        return WordUtils.capitalizeFully(string, separators).replace(String.valueOf(separator), " ");
+        return WordUtils.capitalize(string.toLowerCase(Locale.ROOT), separators).replace(String.valueOf(separator), " ");
     }
 
     /**
@@ -28,7 +32,7 @@ public class StringUtil {
      *
      * @param string String to reformat
      * @return Reformatted string
-     * @see com.Acrobot.Breeze.Utils.StringUtil#capitalizeFirstLetter(String, char)
+     * @see StringUtil#capitalizeFirstLetter(String, char)
      */
     public static String capitalizeFirstLetter(String string) {
         return capitalizeFirstLetter(string, ' ');
diff --git a/src/main/java/com/Acrobot/ChestShop/Configuration/Properties.java b/src/main/java/com/Acrobot/ChestShop/Configuration/Properties.java
index f4a7ffc8..6e558955 100644
--- a/src/main/java/com/Acrobot/ChestShop/Configuration/Properties.java
+++ b/src/main/java/com/Acrobot/ChestShop/Configuration/Properties.java
@@ -14,6 +14,7 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.EnumSet;
 import java.util.LinkedHashSet;
+import java.util.Locale;
 import java.util.Set;
 import java.util.logging.Level;
 
@@ -42,7 +43,7 @@ public class Properties {
                             set.add((Material) o);
                         } else if (o instanceof String) {
                             try {
-                                set.add(Material.getMaterial(((String) o).toUpperCase()));
+                                set.add(Material.getMaterial(((String) o).toUpperCase(Locale.ROOT)));
                             } catch (IllegalArgumentException e) {
                                 ChestShop.getBukkitLogger().log(Level.WARNING, o + " is not a valid Material name in the config!");
                             }
diff --git a/src/main/java/com/Acrobot/ChestShop/Listeners/Modules/PriceRestrictionModule.java b/src/main/java/com/Acrobot/ChestShop/Listeners/Modules/PriceRestrictionModule.java
index bec2604d..9de7a891 100644
--- a/src/main/java/com/Acrobot/ChestShop/Listeners/Modules/PriceRestrictionModule.java
+++ b/src/main/java/com/Acrobot/ChestShop/Listeners/Modules/PriceRestrictionModule.java
@@ -15,6 +15,7 @@ import org.bukkit.inventory.ItemStack;
 import java.io.File;
 import java.io.IOException;
 import java.math.BigDecimal;
+import java.util.Locale;
 import java.util.logging.Level;
 
 import static com.Acrobot.ChestShop.Events.PreShopCreationEvent.CreationOutcome.BUY_PRICE_ABOVE_MAX;
@@ -84,7 +85,7 @@ public class PriceRestrictionModule implements Listener {
             for (String typeId : section.getKeys(false)) {
                 Material material = Material.matchMaterial(typeId);
                 if (material != null) {
-                    configuration.set(sectionPath + "." + material.toString().toLowerCase(), configuration.get(sectionPath + "." + typeId));
+                    configuration.set(sectionPath + "." + material.toString().toLowerCase(Locale.ROOT), configuration.get(sectionPath + "." + typeId));
                     configuration.set(sectionPath + "." + typeId, null);
                 }
             }
@@ -101,7 +102,7 @@ public class PriceRestrictionModule implements Listener {
             return;
         }
 
-        String itemType = material.getType().toString().toLowerCase();
+        String itemType = material.getType().toString().toLowerCase(Locale.ROOT);
         int amount;
         try {
             amount = Integer.parseInt(event.getSignLine(QUANTITY_LINE));
diff --git a/src/main/java/com/Acrobot/ChestShop/Listeners/PreShopCreation/PermissionChecker.java b/src/main/java/com/Acrobot/ChestShop/Listeners/PreShopCreation/PermissionChecker.java
index b5ab7bfe..93b1d4fb 100644
--- a/src/main/java/com/Acrobot/ChestShop/Listeners/PreShopCreation/PermissionChecker.java
+++ b/src/main/java/com/Acrobot/ChestShop/Listeners/PreShopCreation/PermissionChecker.java
@@ -10,6 +10,8 @@ import org.bukkit.event.EventHandler;
 import org.bukkit.event.Listener;
 import org.bukkit.inventory.ItemStack;
 
+import java.util.Locale;
+
 import static com.Acrobot.ChestShop.Events.PreShopCreationEvent.CreationOutcome.NO_PERMISSION;
 import static com.Acrobot.ChestShop.Permission.*;
 import static com.Acrobot.ChestShop.Signs.ChestShopSign.ITEM_LINE;
@@ -39,7 +41,7 @@ public class PermissionChecker implements Listener {
             return;
         }
 
-        String matID = item.getType().toString().toLowerCase();
+        String matID = item.getType().toString().toLowerCase(Locale.ROOT);
         if (PriceUtil.hasBuyPrice(priceLine)) {
             if (Permission.has(player, SHOP_CREATION_BUY_ID + matID)) {
                 return;
diff --git a/src/main/java/com/Acrobot/ChestShop/Listeners/PreShopCreation/PriceChecker.java b/src/main/java/com/Acrobot/ChestShop/Listeners/PreShopCreation/PriceChecker.java
index 9a785278..87260c1b 100644
--- a/src/main/java/com/Acrobot/ChestShop/Listeners/PreShopCreation/PriceChecker.java
+++ b/src/main/java/com/Acrobot/ChestShop/Listeners/PreShopCreation/PriceChecker.java
@@ -7,6 +7,8 @@ import org.bukkit.event.EventHandler;
 import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
 
+import java.util.Locale;
+
 import static com.Acrobot.Breeze.Utils.PriceUtil.isPrice;
 import static com.Acrobot.ChestShop.Events.PreShopCreationEvent.CreationOutcome.INVALID_PRICE;
 import static com.Acrobot.ChestShop.Signs.ChestShopSign.PRICE_LINE;
@@ -18,7 +20,7 @@ public class PriceChecker implements Listener {
 
     @EventHandler(priority = EventPriority.LOWEST)
     public static void onPreShopCreation(PreShopCreationEvent event) {
-        String line = event.getSignLine(PRICE_LINE).toUpperCase();
+        String line = event.getSignLine(PRICE_LINE).toUpperCase(Locale.ROOT);
         if (Properties.PRICE_PRECISION <= 0) {
             line = line.replaceAll("\\.\\d*", ""); //remove too many decimal places
         } else {
diff --git a/src/main/java/com/Acrobot/ChestShop/Listeners/PreTransaction/PermissionChecker.java b/src/main/java/com/Acrobot/ChestShop/Listeners/PreTransaction/PermissionChecker.java
index 861b2d47..f8eb6ca6 100644
--- a/src/main/java/com/Acrobot/ChestShop/Listeners/PreTransaction/PermissionChecker.java
+++ b/src/main/java/com/Acrobot/ChestShop/Listeners/PreTransaction/PermissionChecker.java
@@ -8,6 +8,8 @@ import org.bukkit.event.EventHandler;
 import org.bukkit.event.Listener;
 import org.bukkit.inventory.ItemStack;
 
+import java.util.Locale;
+
 import static com.Acrobot.ChestShop.Events.PreTransactionEvent.TransactionOutcome.CLIENT_DOES_NOT_HAVE_PERMISSION;
 import static com.Acrobot.ChestShop.Events.TransactionEvent.TransactionType.BUY;
 
@@ -25,7 +27,7 @@ public class PermissionChecker implements Listener {
         TransactionEvent.TransactionType transactionType = event.getTransactionType();
 
         for (ItemStack stock : event.getStock()) {
-            String matID = stock.getType().toString().toLowerCase();
+            String matID = stock.getType().toString().toLowerCase(Locale.ROOT);
 
             boolean hasPerm;
 
diff --git a/src/main/java/com/Acrobot/ChestShop/Permission.java b/src/main/java/com/Acrobot/ChestShop/Permission.java
index f059a989..7ffda938 100644
--- a/src/main/java/com/Acrobot/ChestShop/Permission.java
+++ b/src/main/java/com/Acrobot/ChestShop/Permission.java
@@ -4,6 +4,7 @@ import org.bukkit.Bukkit;
 import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 
+import java.util.Locale;
 import java.util.Optional;
 
 /**
@@ -54,7 +55,7 @@ public enum Permission {
     }
 
     public static boolean has(CommandSender sender, String node) {
-        return sender.hasPermission(node) || sender.hasPermission(node.toLowerCase());
+        return sender.hasPermission(node) || sender.hasPermission(node.toLowerCase(Locale.ROOT));
     }
 
     public static boolean otherName(Player player, String name) {
@@ -64,15 +65,15 @@ public enum Permission {
     public static boolean otherName(Player player, Permission base, String name) {
         boolean hasBase = base != OTHER_NAME && otherName(player, OTHER_NAME, name);
         if (hasBase || has(player, base + ".*")) {
-            return !hasPermissionSetFalse(player, base+ "." + name) && !hasPermissionSetFalse(player, base + "." + name.toLowerCase());
+            return !hasPermissionSetFalse(player, base+ "." + name) && !hasPermissionSetFalse(player, base + "." + name.toLowerCase(Locale.ROOT));
         }
 
-        return has(player, base + "." + name) || has(player, base + "." + name.toLowerCase());
+        return has(player, base + "." + name) || has(player, base + "." + name.toLowerCase(Locale.ROOT));
     }
 
     private static boolean hasPermissionSetFalse(CommandSender sender, String permission) {
         return (sender.isPermissionSet(permission) && !sender.hasPermission(permission))
-                || (sender.isPermissionSet(permission.toLowerCase()) && !sender.hasPermission(permission.toLowerCase()));
+                || (sender.isPermissionSet(permission.toLowerCase(Locale.ROOT)) && !sender.hasPermission(permission.toLowerCase(Locale.ROOT)));
     }
 
     public static org.bukkit.permissions.Permission getPermission(Permission permission) {
diff --git a/src/main/java/com/Acrobot/ChestShop/Signs/ChestShopSign.java b/src/main/java/com/Acrobot/ChestShop/Signs/ChestShopSign.java
index 3ad8ac87..ba2485ef 100644
--- a/src/main/java/com/Acrobot/ChestShop/Signs/ChestShopSign.java
+++ b/src/main/java/com/Acrobot/ChestShop/Signs/ChestShopSign.java
@@ -19,6 +19,7 @@ import org.bukkit.entity.Player;
 import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.InventoryHolder;
 
+import java.util.Locale;
 import java.util.regex.Pattern;
 
 /**
@@ -56,7 +57,7 @@ public class ChestShopSign {
 
     public static boolean isValid(String[] line) {
         line = StringUtil.stripColourCodes(line);
-        return isValidPreparedSign(line) && (line[PRICE_LINE].toUpperCase().contains("B") || line[PRICE_LINE].toUpperCase().contains("S")) && !line[NAME_LINE].isEmpty();
+        return isValidPreparedSign(line) && (line[PRICE_LINE].toUpperCase(Locale.ROOT).contains("B") || line[PRICE_LINE].toUpperCase(Locale.ROOT).contains("S")) && !line[NAME_LINE].isEmpty();
     }
 
     public static boolean isValid(Block sign) {
diff --git a/src/main/java/com/Acrobot/ChestShop/UUIDs/NameManager.java b/src/main/java/com/Acrobot/ChestShop/UUIDs/NameManager.java
index cc3a5997..e45cfbba 100644
--- a/src/main/java/com/Acrobot/ChestShop/UUIDs/NameManager.java
+++ b/src/main/java/com/Acrobot/ChestShop/UUIDs/NameManager.java
@@ -22,6 +22,7 @@ import org.bukkit.event.Listener;
 
 import java.sql.SQLException;
 import java.util.Date;
+import java.util.Locale;
 import java.util.UUID;
 import java.util.concurrent.ExecutionException;
 import java.util.logging.Level;
@@ -164,14 +165,14 @@ public class NameManager implements Listener {
             } catch (ExecutionException ignored) {}
         }
 
-        if (account == null && searchOfflinePlayer && !invalidPlayers.contains(shortName.toLowerCase())) {
+        if (account == null && searchOfflinePlayer && !invalidPlayers.contains(shortName.toLowerCase(Locale.ROOT))) {
             // no account with that shortname was found, try to get an offline player with that name
             OfflinePlayer offlinePlayer = ChestShop.getBukkitServer().getOfflinePlayer(shortName);
             if (offlinePlayer != null && offlinePlayer.getName() != null && offlinePlayer.getUniqueId() != null
                     && offlinePlayer.getUniqueId().version() == uuidVersion) {
                 account = storeUsername(new PlayerDTO(offlinePlayer.getUniqueId(), offlinePlayer.getName()));
             } else {
-                invalidPlayers.put(shortName.toLowerCase(), true);
+                invalidPlayers.put(shortName.toLowerCase(Locale.ROOT), true);
             }
         }
         return account;
diff --git a/src/main/java/com/Acrobot/ChestShop/Updater/Updater.java b/src/main/java/com/Acrobot/ChestShop/Updater/Updater.java
index 4ed8e205..6cacbc42 100644
--- a/src/main/java/com/Acrobot/ChestShop/Updater/Updater.java
+++ b/src/main/java/com/Acrobot/ChestShop/Updater/Updater.java
@@ -17,6 +17,7 @@ import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLConnection;
 import java.util.Enumeration;
+import java.util.Locale;
 import java.util.logging.Level;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
@@ -241,7 +242,7 @@ public class Updater {
         this.waitForThread();
         if (this.versionType != null) {
             for (ReleaseType type : ReleaseType.values()) {
-                if (this.versionType.equals(type.name().toLowerCase())) {
+                if (this.versionType.equals(type.name().toLowerCase(Locale.ROOT))) {
                     return type;
                 }
             }