diff --git a/composer.json b/composer.json
index 3056ffa82..aa3ceafe4 100644
--- a/composer.json
+++ b/composer.json
@@ -32,7 +32,8 @@
       "pocketmine/binaryutils": "^0.1.0",
       "pocketmine/nbt": "dev-master",
       "pocketmine/math": "dev-master",
-      "pocketmine/snooze": "^0.1.0"
+      "pocketmine/snooze": "^0.1.0",
+      "daverandom/callback-validator": "dev-master"
    },
    "autoload": {
       "psr-4": {
diff --git a/composer.lock b/composer.lock
index 9d8246e6a..8269f9a20 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,8 +4,48 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "d6cbb4a2c58dae0906bf9c13ef4a1f2c",
+    "content-hash": "4793017ff4b236529dc5072bd06f8754",
     "packages": [
+        {
+            "name": "daverandom/callback-validator",
+            "version": "dev-master",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/DaveRandom/CallbackValidator.git",
+                "reference": "d87a08cddbc6099816ed01e50ce25cdfc43b542f"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/DaveRandom/CallbackValidator/zipball/d87a08cddbc6099816ed01e50ce25cdfc43b542f",
+                "reference": "d87a08cddbc6099816ed01e50ce25cdfc43b542f",
+                "shasum": ""
+            },
+            "require": {
+                "ext-reflection": "*",
+                "php": ">=7.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^6.0"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "DaveRandom\\CallbackValidator\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Chris Wright",
+                    "email": "cw@daverandom.com"
+                }
+            ],
+            "description": "Tools for validating callback signatures",
+            "time": "2017-04-03T15:22:41+00:00"
+        },
         {
             "name": "fgrosse/phpasn1",
             "version": "v2.1.1",
@@ -377,7 +417,8 @@
         "pocketmine/raklib": 20,
         "pocketmine/spl": 20,
         "pocketmine/nbt": 20,
-        "pocketmine/math": 20
+        "pocketmine/math": 20,
+        "daverandom/callback-validator": 20
     },
     "prefer-stable": false,
     "prefer-lowest": false,
diff --git a/src/pocketmine/scheduler/AsyncPool.php b/src/pocketmine/scheduler/AsyncPool.php
index efbb0b5b0..6b9d148f1 100644
--- a/src/pocketmine/scheduler/AsyncPool.php
+++ b/src/pocketmine/scheduler/AsyncPool.php
@@ -23,6 +23,8 @@ declare(strict_types=1);
 
 namespace pocketmine\scheduler;
 
+use pocketmine\utils\Utils;
+
 /**
  * Manages general-purpose worker threads used for processing asynchronous tasks, and the tasks submitted to those
  * workers.
@@ -84,6 +86,7 @@ class AsyncPool{
 	 * @param \Closure $hook
 	 */
 	public function addWorkerStartHook(\Closure $hook) : void{
+		Utils::validateCallableSignature(function(int $worker) : void{}, $hook);
 		$this->workerStartHooks[spl_object_hash($hook)] = $hook;
 		foreach($this->workers as $i => $worker){
 			$hook($i);
diff --git a/src/pocketmine/scheduler/ClosureTask.php b/src/pocketmine/scheduler/ClosureTask.php
index 8ada271ff..f023173d4 100644
--- a/src/pocketmine/scheduler/ClosureTask.php
+++ b/src/pocketmine/scheduler/ClosureTask.php
@@ -45,6 +45,7 @@ class ClosureTask extends Task{
 	 * @param \Closure $closure Must accept only ONE parameter, $currentTick
 	 */
 	public function __construct(\Closure $closure){
+		Utils::validateCallableSignature(function(int $currentTick) : void{}, $closure);
 		$this->closure = $closure;
 	}
 
diff --git a/src/pocketmine/utils/Utils.php b/src/pocketmine/utils/Utils.php
index 5989de29f..bd13a3c6d 100644
--- a/src/pocketmine/utils/Utils.php
+++ b/src/pocketmine/utils/Utils.php
@@ -27,6 +27,7 @@ declare(strict_types=1);
 
 namespace pocketmine\utils;
 
+use DaveRandom\CallbackValidator\CallbackType;
 use pocketmine\ThreadManager;
 
 /**
@@ -550,4 +551,20 @@ class Utils{
 			throw new \InvalidArgumentException("Class $className cannot be constructed");
 		}
 	}
+
+	/**
+	 * Verifies that the given callable is compatible with the desired signature. Throws a TypeError if they are
+	 * incompatible.
+	 *
+	 * @param callable $signature Dummy callable with the required parameters and return type
+	 * @param callable $subject Callable to check the signature of
+	 *
+	 * @throws \DaveRandom\CallbackValidator\InvalidCallbackException
+	 * @throws \TypeError
+	 */
+	public static function validateCallableSignature(callable $signature, callable $subject) : void{
+		if(!($sigType = CallbackType::createFromCallable($signature))->isSatisfiedBy($subject)){
+			throw new \TypeError("Declaration of callable `" . CallbackType::createFromCallable($subject) . "` must be compatible with `" . $sigType . "`");
+		}
+	}
 }