diff --git a/src/pocketmine/Server.php b/src/pocketmine/Server.php
index 99ada2658b..82564f49db 100644
--- a/src/pocketmine/Server.php
+++ b/src/pocketmine/Server.php
@@ -2343,7 +2343,7 @@ class Server{
 		$p->dataPacket($pk);
 	}
 
-	private function checkTickUpdates($currentTick, $tickTime){
+	private function checkTickUpdates(int $currentTick, float $tickTime) : void{
 		foreach($this->players as $p){
 			if(!$p->loggedIn and ($tickTime - $p->creationTime) >= 10){
 				$p->close("", "Login timeout");
diff --git a/src/pocketmine/block/Leaves.php b/src/pocketmine/block/Leaves.php
index 6edf9c8c1e..bd0d459f02 100644
--- a/src/pocketmine/block/Leaves.php
+++ b/src/pocketmine/block/Leaves.php
@@ -67,7 +67,7 @@ class Leaves extends Transparent{
 	}
 
 
-	protected function findLog(Block $pos, array $visited, $distance, &$check, $fromSide = null) : bool{
+	protected function findLog(Block $pos, array $visited, int $distance, &$check, ?int $fromSide = null) : bool{
 		++$check;
 		$index = $pos->x . "." . $pos->y . "." . $pos->z;
 		if(isset($visited[$index])){
diff --git a/src/pocketmine/command/PluginCommand.php b/src/pocketmine/command/PluginCommand.php
index 59a1eb17e1..4c7757b590 100644
--- a/src/pocketmine/command/PluginCommand.php
+++ b/src/pocketmine/command/PluginCommand.php
@@ -38,7 +38,7 @@ class PluginCommand extends Command implements PluginIdentifiableCommand{
 	 * @param string $name
 	 * @param Plugin $owner
 	 */
-	public function __construct($name, Plugin $owner){
+	public function __construct(string $name, Plugin $owner){
 		parent::__construct($name);
 		$this->owningPlugin = $owner;
 		$this->executor = $owner;
diff --git a/src/pocketmine/event/player/PlayerCommandPreprocessEvent.php b/src/pocketmine/event/player/PlayerCommandPreprocessEvent.php
index be8f4c697b..80283b5ed3 100644
--- a/src/pocketmine/event/player/PlayerCommandPreprocessEvent.php
+++ b/src/pocketmine/event/player/PlayerCommandPreprocessEvent.php
@@ -43,7 +43,7 @@ class PlayerCommandPreprocessEvent extends PlayerEvent implements Cancellable{
 	 * @param Player $player
 	 * @param string $message
 	 */
-	public function __construct(Player $player, $message){
+	public function __construct(Player $player, string $message){
 		$this->player = $player;
 		$this->message = $message;
 	}
diff --git a/src/pocketmine/level/Level.php b/src/pocketmine/level/Level.php
index 10acf678e3..d6b125a332 100644
--- a/src/pocketmine/level/Level.php
+++ b/src/pocketmine/level/Level.php
@@ -850,7 +850,7 @@ class Level implements ChunkManager, Metadatable{
 	 * @param int      $flags
 	 * @param bool     $optimizeRebuilds
 	 */
-	public function sendBlocks(array $target, array $blocks, $flags = UpdateBlockPacket::FLAG_NONE, bool $optimizeRebuilds = false){
+	public function sendBlocks(array $target, array $blocks, int $flags = UpdateBlockPacket::FLAG_NONE, bool $optimizeRebuilds = false){
 		$packets = [];
 		if($optimizeRebuilds){
 			$chunks = [];
@@ -2067,7 +2067,7 @@ class Level implements ChunkManager, Metadatable{
 	 *
 	 * @return Entity[]
 	 */
-	public function getChunkEntities($X, $Z) : array{
+	public function getChunkEntities(int $X, int $Z) : array{
 		return ($chunk = $this->getChunk($X, $Z)) !== null ? $chunk->getEntities() : [];
 	}
 
@@ -2079,7 +2079,7 @@ class Level implements ChunkManager, Metadatable{
 	 *
 	 * @return Tile[]
 	 */
-	public function getChunkTiles($X, $Z) : array{
+	public function getChunkTiles(int $X, int $Z) : array{
 		return ($chunk = $this->getChunk($X, $Z)) !== null ? $chunk->getTiles() : [];
 	}
 
diff --git a/src/pocketmine/level/SimpleChunkManager.php b/src/pocketmine/level/SimpleChunkManager.php
index 4c4e673bf0..051176d148 100644
--- a/src/pocketmine/level/SimpleChunkManager.php
+++ b/src/pocketmine/level/SimpleChunkManager.php
@@ -39,7 +39,7 @@ class SimpleChunkManager implements ChunkManager{
 	 * @param int $seed
 	 * @param int $worldHeight
 	 */
-	public function __construct($seed, int $worldHeight = Level::Y_MAX){
+	public function __construct(int $seed, int $worldHeight = Level::Y_MAX){
 		$this->seed = $seed;
 		$this->worldHeight = $worldHeight;
 	}
diff --git a/src/pocketmine/level/format/Chunk.php b/src/pocketmine/level/format/Chunk.php
index 1415a98198..f1156a487e 100644
--- a/src/pocketmine/level/format/Chunk.php
+++ b/src/pocketmine/level/format/Chunk.php
@@ -186,7 +186,7 @@ class Chunk{
 	 *
 	 * @return bool
 	 */
-	public function setBlock(int $x, int $y, int $z, $blockId = null, $meta = null) : bool{
+	public function setBlock(int $x, int $y, int $z, ?int $blockId = null, ?int $meta = null) : bool{
 		if($this->getSubChunk($y >> 4, true)->setBlock($x, $y & 0x0f, $z, $blockId !== null ? ($blockId & 0xff) : null, $meta !== null ? ($meta & 0x0f) : null)){
 			$this->hasChanged = true;
 			return true;
diff --git a/src/pocketmine/level/format/EmptySubChunk.php b/src/pocketmine/level/format/EmptySubChunk.php
index 5ffb2942d3..7d8c22544b 100644
--- a/src/pocketmine/level/format/EmptySubChunk.php
+++ b/src/pocketmine/level/format/EmptySubChunk.php
@@ -59,7 +59,7 @@ class EmptySubChunk implements SubChunkInterface{
 		return 0;
 	}
 
-	public function setBlock(int $x, int $y, int $z, $id = null, $data = null) : bool{
+	public function setBlock(int $x, int $y, int $z, ?int $id = null, ?int $data = null) : bool{
 		return false;
 	}
 
diff --git a/src/pocketmine/level/format/SubChunk.php b/src/pocketmine/level/format/SubChunk.php
index 74c6625212..33ce57d6b5 100644
--- a/src/pocketmine/level/format/SubChunk.php
+++ b/src/pocketmine/level/format/SubChunk.php
@@ -93,7 +93,7 @@ class SubChunk implements SubChunkInterface{
 		}
 	}
 
-	public function setBlock(int $x, int $y, int $z, $id = null, $data = null) : bool{
+	public function setBlock(int $x, int $y, int $z, ?int $id = null, ?int $data = null) : bool{
 		$i = ($x << 8) | ($z << 4) | $y;
 		$changed = false;
 		if($id !== null){
diff --git a/src/pocketmine/level/format/SubChunkInterface.php b/src/pocketmine/level/format/SubChunkInterface.php
index 6cfaf945c1..b0c8164035 100644
--- a/src/pocketmine/level/format/SubChunkInterface.php
+++ b/src/pocketmine/level/format/SubChunkInterface.php
@@ -87,7 +87,7 @@ interface SubChunkInterface{
 	 *
 	 * @return bool
 	 */
-	public function setBlock(int $x, int $y, int $z, $id = null, $data = null) : bool;
+	public function setBlock(int $x, int $y, int $z, ?int $id = null, ?int $data = null) : bool;
 
 	/**
 	 * @param int $x
diff --git a/src/pocketmine/level/generator/populator/TallGrass.php b/src/pocketmine/level/generator/populator/TallGrass.php
index 2aab240e39..a601799466 100644
--- a/src/pocketmine/level/generator/populator/TallGrass.php
+++ b/src/pocketmine/level/generator/populator/TallGrass.php
@@ -56,12 +56,12 @@ class TallGrass extends Populator{
 		}
 	}
 
-	private function canTallGrassStay($x, $y, $z){
+	private function canTallGrassStay(int $x, int $y, int $z) : bool{
 		$b = $this->level->getBlockIdAt($x, $y, $z);
 		return ($b === Block::AIR or $b === Block::SNOW_LAYER) and $this->level->getBlockIdAt($x, $y - 1, $z) === Block::GRASS;
 	}
 
-	private function getHighestWorkableBlock($x, $z){
+	private function getHighestWorkableBlock(int $x, int $z) : int{
 		for($y = 127; $y >= 0; --$y){
 			$b = $this->level->getBlockIdAt($x, $y, $z);
 			if($b !== Block::AIR and $b !== Block::LEAVES and $b !== Block::LEAVES2 and $b !== Block::SNOW_LAYER){
diff --git a/src/pocketmine/level/generator/populator/Tree.php b/src/pocketmine/level/generator/populator/Tree.php
index 85bb071eb3..cbe8e6bcee 100644
--- a/src/pocketmine/level/generator/populator/Tree.php
+++ b/src/pocketmine/level/generator/populator/Tree.php
@@ -63,7 +63,7 @@ class Tree extends Populator{
 		}
 	}
 
-	private function getHighestWorkableBlock($x, $z){
+	private function getHighestWorkableBlock(int $x, int $z) : int{
 		for($y = 127; $y > 0; --$y){
 			$b = $this->level->getBlockIdAt($x, $y, $z);
 			if($b === Block::DIRT or $b === Block::GRASS){
diff --git a/src/pocketmine/network/query/QueryHandler.php b/src/pocketmine/network/query/QueryHandler.php
index 1cb9de5014..ea2fa81749 100644
--- a/src/pocketmine/network/query/QueryHandler.php
+++ b/src/pocketmine/network/query/QueryHandler.php
@@ -70,7 +70,7 @@ class QueryHandler{
 		$this->token = random_bytes(16);
 	}
 
-	public static function getTokenString($token, $salt){
+	public static function getTokenString(string $token, string $salt) : int{
 		return Binary::readInt(substr(hash("sha512", $salt . ":" . $token, true), 7, 4));
 	}
 
diff --git a/src/pocketmine/network/rcon/RCONInstance.php b/src/pocketmine/network/rcon/RCONInstance.php
index 64224ff770..495f6ecccd 100644
--- a/src/pocketmine/network/rcon/RCONInstance.php
+++ b/src/pocketmine/network/rcon/RCONInstance.php
@@ -71,15 +71,15 @@ class RCONInstance extends Thread{
 		$this->start(PTHREADS_INHERIT_NONE);
 	}
 
-	private function writePacket($client, $requestID, $packetType, $payload){
-		$pk = Binary::writeLInt((int) $requestID)
-			. Binary::writeLInt((int) $packetType)
+	private function writePacket($client, int $requestID, int $packetType, string $payload){
+		$pk = Binary::writeLInt($requestID)
+			. Binary::writeLInt($packetType)
 			. $payload
 			. "\x00\x00"; //Terminate payload and packet
 		return socket_write($client, Binary::writeLInt(strlen($pk)) . $pk);
 	}
 
-	private function readPacket($client, &$requestID, &$packetType, &$payload){
+	private function readPacket($client, ?int &$requestID, ?int &$packetType, ?string &$payload){
 		$d = socket_read($client, 4);
 		if($this->stop){
 			return false;
diff --git a/src/pocketmine/permission/Permission.php b/src/pocketmine/permission/Permission.php
index 8b0942dea1..2e4ff4b7a4 100644
--- a/src/pocketmine/permission/Permission.php
+++ b/src/pocketmine/permission/Permission.php
@@ -178,7 +178,7 @@ class Permission{
 	 *
 	 * @return Permission|null Permission if $name is a string, null if it's a Permission
 	 */
-	public function addParent($name, $value){
+	public function addParent($name, bool $value){
 		if($name instanceof Permission){
 			$name->getChildren()[$this->getName()] = $value;
 			$name->recalculatePermissibles();
diff --git a/src/pocketmine/plugin/PharPluginLoader.php b/src/pocketmine/plugin/PharPluginLoader.php
index 5e78d13760..40c7a90648 100644
--- a/src/pocketmine/plugin/PharPluginLoader.php
+++ b/src/pocketmine/plugin/PharPluginLoader.php
@@ -112,7 +112,7 @@ class PharPluginLoader implements PluginLoader{
 	 * @param string            $dataFolder
 	 * @param string            $file
 	 */
-	private function initPlugin(PluginBase $plugin, PluginDescription $description, $dataFolder, $file){
+	private function initPlugin(PluginBase $plugin, PluginDescription $description, string $dataFolder, string $file){
 		$plugin->init($this, $this->server, $description, $dataFolder, $file);
 		$plugin->onLoad();
 	}
diff --git a/src/pocketmine/plugin/PluginBase.php b/src/pocketmine/plugin/PluginBase.php
index de66a85d2f..d90f51a763 100644
--- a/src/pocketmine/plugin/PluginBase.php
+++ b/src/pocketmine/plugin/PluginBase.php
@@ -113,7 +113,7 @@ abstract class PluginBase implements Plugin{
 		return $this->description;
 	}
 
-	final public function init(PluginLoader $loader, Server $server, PluginDescription $description, $dataFolder, $file){
+	final public function init(PluginLoader $loader, Server $server, PluginDescription $description, string $dataFolder, string $file){
 		if(!$this->initialized){
 			$this->initialized = true;
 			$this->loader = $loader;
diff --git a/src/pocketmine/tile/Tile.php b/src/pocketmine/tile/Tile.php
index d980b841a2..88b048afe0 100644
--- a/src/pocketmine/tile/Tile.php
+++ b/src/pocketmine/tile/Tile.php
@@ -110,13 +110,13 @@ abstract class Tile extends Position{
 	}
 
 	/**
-	 * @param       $className
-	 * @param array $saveNames
+	 * @param string $className
+	 * @param array  $saveNames
 	 *
 	 * @return bool
 	 * @throws \ReflectionException
 	 */
-	public static function registerTile($className, array $saveNames = []) : bool{
+	public static function registerTile(string $className, array $saveNames = []) : bool{
 		$class = new \ReflectionClass($className);
 		if(is_a($className, Tile::class, true) and !$class->isAbstract()){
 			$shortName = $class->getShortName();
diff --git a/src/pocketmine/utils/Utils.php b/src/pocketmine/utils/Utils.php
index 82b9aed6c9..290f5bd30e 100644
--- a/src/pocketmine/utils/Utils.php
+++ b/src/pocketmine/utils/Utils.php
@@ -569,7 +569,7 @@ class Utils{
 	 *
 	 * @return int
 	 */
-	public static function getReferenceCount($value, $includeCurrent = true){
+	public static function getReferenceCount($value, bool $includeCurrent = true){
 		ob_start();
 		debug_zval_dump($value);
 		$ret = explode("\n", ob_get_contents());