diff --git a/pom.xml b/pom.xml
index e40a75d..46fafea 100644
--- a/pom.xml
+++ b/pom.xml
@@ -6,7 +6,7 @@
 
     <groupId>gamemodecommandfix</groupId>
     <artifactId>GamemodeCommandFix</artifactId>
-    <version>1.0.1</version>
+    <version>1.0.2</version>
     <packaging>jar</packaging>
 
     <name>GamemodeCommandFix</name>
diff --git a/src/main/java/com/yj0524/commands/Gm.java b/src/main/java/com/yj0524/commands/Gm.java
index 22c20dc..6930795 100644
--- a/src/main/java/com/yj0524/commands/Gm.java
+++ b/src/main/java/com/yj0524/commands/Gm.java
@@ -9,90 +9,93 @@
 public class Gm implements CommandExecutor {
     @Override
     public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
-        // /gm <0, 1, 2, 3, survival, creative, adventure, spectator> [player]
-        if (args.length == 1) {
-            if (args[0].equalsIgnoreCase("0") || args[0].equalsIgnoreCase("survival")) {
-                if (sender instanceof Player) {
-                    ((Player) sender).setGameMode(GameMode.SURVIVAL);
-                    sender.sendMessage("Gamemode has been changed to survival.");
-                    return true;
-                }
-                sender.sendMessage("You must be a player to use this command.");
-            }
-            if (args[0].equalsIgnoreCase("1") || args[0].equalsIgnoreCase("creative")) {
-                if (sender instanceof Player) {
-                    ((Player) sender).setGameMode(GameMode.CREATIVE);
-                    sender.sendMessage("Gamemode has been changed to creative.");
-                    return true;
-                }
-                sender.sendMessage("You must be a player to use this command.");
-            }
-            if (args[0].equalsIgnoreCase("2") || args[0].equalsIgnoreCase("adventure")) {
-                if (sender instanceof Player) {
-                    ((Player) sender).setGameMode(GameMode.ADVENTURE);
-                    sender.sendMessage("Gamemode has been changed to adventure.");
-                    return true;
-                }
-                sender.sendMessage("You must be a player to use this command.");
-            }
-            if (args[0].equalsIgnoreCase("3") || args[0].equalsIgnoreCase("spectator")) {
-                if (sender instanceof Player) {
-                    ((Player) sender).setGameMode(GameMode.SPECTATOR);
-                    sender.sendMessage("Gamemode has been changed to spectator.");
-                    return true;
-                }
-                sender.sendMessage("You must be a player to use this command.");
-            }
-        }
-        if (args.length == 2) {
-            String targetPlayer = args[1];
-            if (sender.getServer().getPlayer(targetPlayer) == null) {
-                sender.sendMessage("§cPlayer not found.");
-                return true;
-            }
-            else {
+        if (sender.isOp()) {
+            // /gm <0, 1, 2, 3, survival, creative, adventure, spectator> [player]
+            if (args.length == 1) {
                 if (args[0].equalsIgnoreCase("0") || args[0].equalsIgnoreCase("survival")) {
                     if (sender instanceof Player) {
-                        sender.getServer().getPlayer(targetPlayer).setGameMode(GameMode.SURVIVAL);
-                        sender.sendMessage("Gamemode for " + args[1] + " has been changed to survival.");
+                        ((Player) sender).setGameMode(GameMode.SURVIVAL);
+                        sender.sendMessage("Gamemode has been changed to survival.");
                         return true;
-                    } else {
-                        sender.sendMessage("You must be a player to use this command.");
                     }
+                    sender.sendMessage("You must be a player to use this command.");
                 }
                 if (args[0].equalsIgnoreCase("1") || args[0].equalsIgnoreCase("creative")) {
                     if (sender instanceof Player) {
-                        sender.getServer().getPlayer(targetPlayer).setGameMode(GameMode.CREATIVE);
-                        sender.sendMessage("Gamemode for " + args[1] + " has been changed to creative.");
+                        ((Player) sender).setGameMode(GameMode.CREATIVE);
+                        sender.sendMessage("Gamemode has been changed to creative.");
                         return true;
-                    } else {
-                        sender.sendMessage("You must be a player to use this command.");
                     }
+                    sender.sendMessage("You must be a player to use this command.");
                 }
                 if (args[0].equalsIgnoreCase("2") || args[0].equalsIgnoreCase("adventure")) {
                     if (sender instanceof Player) {
-                        sender.getServer().getPlayer(targetPlayer).setGameMode(GameMode.ADVENTURE);
-                        sender.sendMessage("Gamemode for " + args[1] + " has been changed to adventure.");
+                        ((Player) sender).setGameMode(GameMode.ADVENTURE);
+                        sender.sendMessage("Gamemode has been changed to adventure.");
                         return true;
-                    } else {
-                        sender.sendMessage("You must be a player to use this command.");
                     }
+                    sender.sendMessage("You must be a player to use this command.");
                 }
                 if (args[0].equalsIgnoreCase("3") || args[0].equalsIgnoreCase("spectator")) {
                     if (sender instanceof Player) {
-                        sender.getServer().getPlayer(targetPlayer).setGameMode(GameMode.SPECTATOR);
-                        sender.sendMessage("Gamemode for " + args[1] + " has been changed to spectator.");
+                        ((Player) sender).setGameMode(GameMode.SPECTATOR);
+                        sender.sendMessage("Gamemode has been changed to spectator.");
                         return true;
-                    } else {
-                        sender.sendMessage("You must be a player to use this command.");
                     }
+                    sender.sendMessage("You must be a player to use this command.");
                 }
             }
-        }
-        else {
-            sender.sendMessage("§cUsage: /gm <0, 1, 2, 3, survival, creative, adventure, spectator> [player]");
+            if (args.length == 2) {
+                String targetPlayer = args[1];
+                if (sender.getServer().getPlayer(targetPlayer) == null) {
+                    sender.sendMessage("§cPlayer not found.");
+                    return true;
+                } else {
+                    if (args[0].equalsIgnoreCase("0") || args[0].equalsIgnoreCase("survival")) {
+                        if (sender instanceof Player) {
+                            sender.getServer().getPlayer(targetPlayer).setGameMode(GameMode.SURVIVAL);
+                            sender.sendMessage("Gamemode for " + args[1] + " has been changed to survival.");
+                            return true;
+                        } else {
+                            sender.sendMessage("You must be a player to use this command.");
+                        }
+                    }
+                    if (args[0].equalsIgnoreCase("1") || args[0].equalsIgnoreCase("creative")) {
+                        if (sender instanceof Player) {
+                            sender.getServer().getPlayer(targetPlayer).setGameMode(GameMode.CREATIVE);
+                            sender.sendMessage("Gamemode for " + args[1] + " has been changed to creative.");
+                            return true;
+                        } else {
+                            sender.sendMessage("You must be a player to use this command.");
+                        }
+                    }
+                    if (args[0].equalsIgnoreCase("2") || args[0].equalsIgnoreCase("adventure")) {
+                        if (sender instanceof Player) {
+                            sender.getServer().getPlayer(targetPlayer).setGameMode(GameMode.ADVENTURE);
+                            sender.sendMessage("Gamemode for " + args[1] + " has been changed to adventure.");
+                            return true;
+                        } else {
+                            sender.sendMessage("You must be a player to use this command.");
+                        }
+                    }
+                    if (args[0].equalsIgnoreCase("3") || args[0].equalsIgnoreCase("spectator")) {
+                        if (sender instanceof Player) {
+                            sender.getServer().getPlayer(targetPlayer).setGameMode(GameMode.SPECTATOR);
+                            sender.sendMessage("Gamemode for " + args[1] + " has been changed to spectator.");
+                            return true;
+                        } else {
+                            sender.sendMessage("You must be a player to use this command.");
+                        }
+                    }
+                }
+            } else {
+                sender.sendMessage("§cUsage: /gm <0, 1, 2, 3, survival, creative, adventure, spectator> [player]");
+                return true;
+            }
+            return false;
+        } else {
+            sender.sendMessage("§cYou do not have permission to use this command.");
             return true;
         }
-        return false;
     }
 }