diff --git a/src/pocketmine/command/SimpleCommandMap.php b/src/pocketmine/command/SimpleCommandMap.php
index 78308da68..76e859cd0 100644
--- a/src/pocketmine/command/SimpleCommandMap.php
+++ b/src/pocketmine/command/SimpleCommandMap.php
@@ -302,9 +302,9 @@ class SimpleCommandMap implements CommandMap{
 			}
 
 			$targets = [];
+			$bad = [];
+			$recursive = [];
 
-			$bad = "";
-			$recursive = "";
 			foreach($commandStrings as $commandString){
 				$args = explode(" ", $commandString);
 				$commandName = "";
@@ -312,27 +312,21 @@ class SimpleCommandMap implements CommandMap{
 
 
 				if($command === null){
-					if(strlen($bad) > 0){
-						$bad .= ", ";
-					}
-					$bad .= $commandString;
+					$bad[] = $commandString;
 				}elseif($commandName === $alias){
-					if($recursive !== ""){
-						$recursive .= ", ";
-					}
-					$recursive .= $commandString;
+					$recursive[] = $commandString;
 				}else{
 					$targets[] = $commandString;
 				}
 			}
 
-			if($recursive !== ""){
-				$this->server->getLogger()->warning($this->server->getLanguage()->translateString("pocketmine.command.alias.recursive", [$alias, $recursive]));
+			if(!empty($recursive)){
+				$this->server->getLogger()->warning($this->server->getLanguage()->translateString("pocketmine.command.alias.recursive", [$alias, implode(", ", $recursive)]));
 				continue;
 			}
 
-			if(strlen($bad) > 0){
-				$this->server->getLogger()->warning($this->server->getLanguage()->translateString("pocketmine.command.alias.notFound", [$alias, $bad]));
+			if(!empty($bad)){
+				$this->server->getLogger()->warning($this->server->getLanguage()->translateString("pocketmine.command.alias.notFound", [$alias, implode(", ", $bad)]));
 				continue;
 			}
 
diff --git a/src/pocketmine/command/defaults/PluginsCommand.php b/src/pocketmine/command/defaults/PluginsCommand.php
index c86a59286..e4332b81d 100644
--- a/src/pocketmine/command/defaults/PluginsCommand.php
+++ b/src/pocketmine/command/defaults/PluginsCommand.php
@@ -25,6 +25,7 @@ namespace pocketmine\command\defaults;
 
 use pocketmine\command\CommandSender;
 use pocketmine\lang\TranslationContainer;
+use pocketmine\plugin\Plugin;
 use pocketmine\utils\TextFormat;
 
 class PluginsCommand extends VanillaCommand{
@@ -43,20 +44,12 @@ class PluginsCommand extends VanillaCommand{
 		if(!$this->testPermission($sender)){
 			return true;
 		}
-		$this->sendPluginList($sender);
+
+		$list = array_map(function(Plugin $plugin) : string{
+			return ($plugin->isEnabled() ? TextFormat::GREEN : TextFormat::RED) . $plugin->getDescription()->getFullName();
+		}, $sender->getServer()->getPluginManager()->getPlugins());
+
+		$sender->sendMessage(new TranslationContainer("pocketmine.command.plugins.success", [count($list), implode(TextFormat::WHITE . ", ", $list)]));
 		return true;
 	}
-
-	private function sendPluginList(CommandSender $sender){
-		$list = "";
-		foreach(($plugins = $sender->getServer()->getPluginManager()->getPlugins()) as $plugin){
-			if(strlen($list) > 0){
-				$list .= TextFormat::WHITE . ", ";
-			}
-			$list .= $plugin->isEnabled() ? TextFormat::GREEN : TextFormat::RED;
-			$list .= $plugin->getDescription()->getFullName();
-		}
-
-		$sender->sendMessage(new TranslationContainer("pocketmine.command.plugins.success", [count($plugins), $list]));
-	}
 }
diff --git a/src/pocketmine/command/defaults/TeleportCommand.php b/src/pocketmine/command/defaults/TeleportCommand.php
index b83b21677..899086540 100644
--- a/src/pocketmine/command/defaults/TeleportCommand.php
+++ b/src/pocketmine/command/defaults/TeleportCommand.php
@@ -49,7 +49,7 @@ class TeleportCommand extends VanillaCommand{
 		}
 
 		$args = array_values(array_filter($args, function($arg){
-			return strlen($arg) > 0;
+			return $arg !== "";
 		}));
 		if(count($args) < 1 or count($args) > 6){
 			throw new InvalidCommandSyntaxException();
diff --git a/src/pocketmine/entity/Living.php b/src/pocketmine/entity/Living.php
index ac22eb6ff..b70e42f31 100644
--- a/src/pocketmine/entity/Living.php
+++ b/src/pocketmine/entity/Living.php
@@ -661,13 +661,8 @@ abstract class Living extends Entity implements Damageable{
 				$this->attack($ev);
 			}
 
-			if(!$this->canBreathe()){
-				$this->setBreathing(false);
-				$this->doAirSupplyTick($tickDiff);
+			if($this->doAirSupplyTick($tickDiff)){
 				$hasUpdate = true;
-			}elseif(!$this->isBreathing()){
-				$this->setBreathing(true);
-				$this->setAirSupplyTicks($this->getMaxAirSupplyTicks());
 			}
 		}
 
@@ -696,22 +691,42 @@ abstract class Living extends Entity implements Damageable{
 	}
 
 	/**
-	 * Ticks the entity's air supply when it cannot breathe.
+	 * Ticks the entity's air supply, consuming it when underwater and regenerating it when out of water.
+	 *
 	 * @param int $tickDiff
+	 *
+	 * @return bool
 	 */
-	protected function doAirSupplyTick(int $tickDiff) : void{
-		if(($respirationLevel = $this->armorInventory->getHelmet()->getEnchantmentLevel(Enchantment::RESPIRATION)) <= 0 or
-			lcg_value() <= (1 / ($respirationLevel + 1))
-		){
-			$ticks = $this->getAirSupplyTicks() - $tickDiff;
+	protected function doAirSupplyTick(int $tickDiff) : bool{
+		$ticks = $this->getAirSupplyTicks();
+		$oldTicks = $ticks;
+		if(!$this->canBreathe()){
+			$this->setBreathing(false);
 
-			if($ticks <= -20){
-				$this->setAirSupplyTicks(0);
-				$this->onAirExpired();
-			}else{
-				$this->setAirSupplyTicks($ticks);
+			if(($respirationLevel = $this->armorInventory->getHelmet()->getEnchantmentLevel(Enchantment::RESPIRATION)) <= 0 or
+				lcg_value() <= (1 / ($respirationLevel + 1))
+			){
+				$ticks -= $tickDiff;
+				if($ticks <= -20){
+					$ticks = 0;
+					$this->onAirExpired();
+				}
+			}
+		}elseif(!$this->isBreathing()){
+			if($ticks < ($max = $this->getMaxAirSupplyTicks())){
+				$ticks += $tickDiff * 5;
+			}
+			if($ticks >= $max){
+				$ticks = $max;
+				$this->setBreathing(true);
 			}
 		}
+
+		if($ticks !== $oldTicks){
+			$this->setAirSupplyTicks($ticks);
+		}
+
+		return $ticks !== $oldTicks;
 	}
 
 	/**
diff --git a/src/pocketmine/level/format/io/leveldb/LevelDB.php b/src/pocketmine/level/format/io/leveldb/LevelDB.php
index 71dbcb94f..6c50ac9fc 100644
--- a/src/pocketmine/level/format/io/leveldb/LevelDB.php
+++ b/src/pocketmine/level/format/io/leveldb/LevelDB.php
@@ -377,7 +377,7 @@ class LevelDB extends BaseLevelProvider{
 
 		/** @var CompoundTag[] $entities */
 		$entities = [];
-		if(($entityData = $this->db->get($index . self::TAG_ENTITY)) !== false and strlen($entityData) > 0){
+		if(($entityData = $this->db->get($index . self::TAG_ENTITY)) !== false and $entityData !== ""){
 			$entities = $nbt->read($entityData, true);
 			if(!is_array($entities)){
 				$entities = [$entities];
@@ -392,7 +392,7 @@ class LevelDB extends BaseLevelProvider{
 		}
 
 		$tiles = [];
-		if(($tileData = $this->db->get($index . self::TAG_BLOCK_ENTITY)) !== false and strlen($tileData) > 0){
+		if(($tileData = $this->db->get($index . self::TAG_BLOCK_ENTITY)) !== false and $tileData !== ""){
 			$tiles = $nbt->read($tileData, true);
 			if(!is_array($tiles)){
 				$tiles = [$tiles];
@@ -402,7 +402,7 @@ class LevelDB extends BaseLevelProvider{
 		//TODO: extra data should be converted into blockstorage layers (first they need to be implemented!)
 		/*
 		$extraData = [];
-		if(($extraRawData = $this->db->get($index . self::TAG_BLOCK_EXTRA_DATA)) !== false and strlen($extraRawData) > 0){
+		if(($extraRawData = $this->db->get($index . self::TAG_BLOCK_EXTRA_DATA)) !== false and $extraRawData !== ""){
 			$binaryStream->setBuffer($extraRawData, 0);
 			$count = $binaryStream->getLInt();
 			for($i = 0; $i < $count; ++$i){
diff --git a/src/pocketmine/network/rcon/RCONInstance.php b/src/pocketmine/network/rcon/RCONInstance.php
index 47790e4e6..0c59029a2 100644
--- a/src/pocketmine/network/rcon/RCONInstance.php
+++ b/src/pocketmine/network/rcon/RCONInstance.php
@@ -177,7 +177,7 @@ class RCONInstance extends Thread{
 									$disconnect[$id] = $sock;
 									break;
 								}
-								if(strlen($payload) > 0){
+								if($payload !== ""){
 									$this->cmd = ltrim($payload);
 									$this->synchronized(function(){
 										$this->notifier->wakeupSleeper();
diff --git a/src/pocketmine/permission/BanEntry.php b/src/pocketmine/permission/BanEntry.php
index 790fb8ada..3c91d5839 100644
--- a/src/pocketmine/permission/BanEntry.php
+++ b/src/pocketmine/permission/BanEntry.php
@@ -168,7 +168,7 @@ class BanEntry{
 				}
 
 				$expire = trim(array_shift($str));
-				if(strtolower($expire) !== "forever" and strlen($expire) > 0){
+				if($expire !== "" and strtolower($expire) !== "forever"){
 					$entry->setExpires(self::parseDate($expire));
 				}
 				if(empty($str)){