diff --git a/src/pocketmine/block/Sign.php b/src/pocketmine/block/Sign.php
index 3d055b3cb..0b1a9e416 100644
--- a/src/pocketmine/block/Sign.php
+++ b/src/pocketmine/block/Sign.php
@@ -36,6 +36,7 @@ use pocketmine\utils\TextFormat;
 use function array_map;
 use function assert;
 use function floor;
+use function strlen;
 
 class Sign extends Transparent{
 	/** @var BlockIdentifierFlattened */
@@ -151,8 +152,16 @@ class Sign extends Transparent{
 	 * @param SignText $text
 	 *
 	 * @return bool if the sign update was successful.
+	 * @throws \UnexpectedValueException if the text payload is too large
 	 */
 	public function updateText(Player $author, SignText $text) : bool{
+		$size = 0;
+		foreach($text->getLines() as $line){
+			$size += strlen($line);
+		}
+		if($size > 1000){
+			throw new \UnexpectedValueException($author->getName() . " tried to write $size bytes of text onto a sign (bigger than max 1000)");
+		}
 		$removeFormat = $author->getRemoveFormat();
 		$ev = new SignChangeEvent($this, $author, new SignText(array_map(function(string $line) use ($removeFormat){
 			return TextFormat::clean($line, $removeFormat);
diff --git a/src/pocketmine/command/defaults/WhitelistCommand.php b/src/pocketmine/command/defaults/WhitelistCommand.php
index c5d988f58..aed16e033 100644
--- a/src/pocketmine/command/defaults/WhitelistCommand.php
+++ b/src/pocketmine/command/defaults/WhitelistCommand.php
@@ -115,8 +115,12 @@ class WhitelistCommand extends VanillaCommand{
 		return true;
 	}
 
-	private function badPerm(CommandSender $sender, string $perm) : bool{
-		if(!$sender->hasPermission("pocketmine.command.whitelist.$perm")){
+	private function badPerm(CommandSender $sender, string $subcommand) : bool{
+		static $map = [
+			"on" => "enable",
+			"off" => "disable"
+		];
+		if(!$sender->hasPermission("pocketmine.command.whitelist." . ($map[$subcommand] ?? $subcommand))){
 			$sender->sendMessage($sender->getServer()->getLanguage()->translateString(TextFormat::RED . "%commands.generic.permission"));
 
 			return true;
diff --git a/src/pocketmine/network/mcpe/handler/SimpleSessionHandler.php b/src/pocketmine/network/mcpe/handler/SimpleSessionHandler.php
index b9677d658..8a969d907 100644
--- a/src/pocketmine/network/mcpe/handler/SimpleSessionHandler.php
+++ b/src/pocketmine/network/mcpe/handler/SimpleSessionHandler.php
@@ -464,8 +464,12 @@ class SimpleSessionHandler extends SessionHandler{
 					throw new BadPacketException("Invalid sign text update: " . $e->getMessage(), 0, $e);
 				}
 
-				if(!$block->updateText($this->player, $text)){
-					$this->player->getLevel()->sendBlocks([$this->player], [$block]);
+				try{
+					if(!$block->updateText($this->player, $text)){
+						$this->player->getLevel()->sendBlocks([$this->player], [$block]);
+					}
+				}catch(\UnexpectedValueException $e){
+					throw new BadPacketException($e->getMessage(), 0, $e);
 				}
 
 				return true;