diff --git a/src/world/generator/Flat.php b/src/world/generator/Flat.php
index 06dadc517..29420030f 100644
--- a/src/world/generator/Flat.php
+++ b/src/world/generator/Flat.php
@@ -34,11 +34,9 @@ use pocketmine\world\generator\populator\Populator;
 use function count;
 
 class Flat extends Generator{
-
-	/** @var Chunk */
-	private $chunk;
+	private Chunk $chunk;
 	/** @var Populator[] */
-	private $populators = [];
+	private array $populators = [];
 
 	private FlatGeneratorOptions $options;
 
diff --git a/src/world/generator/Gaussian.php b/src/world/generator/Gaussian.php
index 61b0f86d9..324fc03c4 100644
--- a/src/world/generator/Gaussian.php
+++ b/src/world/generator/Gaussian.php
@@ -26,11 +26,9 @@ namespace pocketmine\world\generator;
 use function exp;
 
 final class Gaussian{
-
-	/** @var int */
-	public $smoothSize;
+	public int $smoothSize;
 	/** @var float[][] */
-	public $kernel = [];
+	public array $kernel = [];
 
 	public function __construct(int $smoothSize){
 		$this->smoothSize = $smoothSize;
diff --git a/src/world/generator/GeneratorManager.php b/src/world/generator/GeneratorManager.php
index 76bda57b6..4bc427da4 100644
--- a/src/world/generator/GeneratorManager.php
+++ b/src/world/generator/GeneratorManager.php
@@ -37,7 +37,7 @@ final class GeneratorManager{
 	 * @var GeneratorManagerEntry[] name => classname mapping
 	 * @phpstan-var array<string, GeneratorManagerEntry>
 	 */
-	private $list = [];
+	private array $list = [];
 
 	public function __construct(){
 		$this->addGenerator(Flat::class, "flat", \Closure::fromCallable(function(string $preset) : ?InvalidGeneratorOptionsException{
diff --git a/src/world/generator/ThreadLocalGeneratorContext.php b/src/world/generator/ThreadLocalGeneratorContext.php
index 56a9b78f6..1fd120437 100644
--- a/src/world/generator/ThreadLocalGeneratorContext.php
+++ b/src/world/generator/ThreadLocalGeneratorContext.php
@@ -31,7 +31,7 @@ final class ThreadLocalGeneratorContext{
 	 * @var self[]
 	 * @phpstan-var array<int, self>
 	 */
-	private static $contexts = [];
+	private static array $contexts = [];
 
 	public static function register(self $context, int $worldId) : void{
 		self::$contexts[$worldId] = $context;
@@ -45,19 +45,11 @@ final class ThreadLocalGeneratorContext{
 		return self::$contexts[$worldId] ?? null;
 	}
 
-	/** @var Generator */
-	private $generator;
-
-	/** @var int */
-	private $worldMinY;
-	/** @var int */
-	private $worldMaxY;
-
-	public function __construct(Generator $generator, int $worldMinY, int $worldMaxY){
-		$this->generator = $generator;
-		$this->worldMinY = $worldMinY;
-		$this->worldMaxY = $worldMaxY;
-	}
+	public function __construct(
+		private Generator $generator,
+		private int $worldMinY,
+		private int $worldMaxY
+	){}
 
 	public function getGenerator() : Generator{ return $this->generator; }
 
diff --git a/src/world/generator/biome/BiomeSelector.php b/src/world/generator/biome/BiomeSelector.php
index f61f534ce..7daf9ee20 100644
--- a/src/world/generator/biome/BiomeSelector.php
+++ b/src/world/generator/biome/BiomeSelector.php
@@ -30,16 +30,14 @@ use pocketmine\world\biome\UnknownBiome;
 use pocketmine\world\generator\noise\Simplex;
 
 abstract class BiomeSelector{
-	/** @var Simplex */
-	private $temperature;
-	/** @var Simplex */
-	private $rainfall;
+	private Simplex $temperature;
+	private Simplex $rainfall;
 
 	/**
 	 * @var Biome[]|\SplFixedArray
 	 * @phpstan-var \SplFixedArray<Biome>
 	 */
-	private $map = null;
+	private \SplFixedArray $map = null;
 
 	public function __construct(Random $random){
 		$this->temperature = new Simplex($random, 2, 1 / 16, 1 / 512);