diff --git a/src/scheduler/AsyncTask.php b/src/scheduler/AsyncTask.php
index 754eaf65d..9d69bda5b 100644
--- a/src/scheduler/AsyncTask.php
+++ b/src/scheduler/AsyncTask.php
@@ -61,12 +61,12 @@ use function spl_object_id;
  */
 abstract class AsyncTask extends Runnable{
 	/**
-	 * @var \ArrayObject|mixed[]|null object hash => mixed data
-	 * @phpstan-var \ArrayObject<int, array<string, mixed>>|null
+	 * @var mixed[][] object hash => mixed data
+	 * @phpstan-var array<int, array<string, mixed>>
 	 *
-	 * Used to store objects which are only needed on one thread and should not be serialized.
+	 * Used to store thread-local data to be used by onCompletion().
 	 */
-	private static ?\ArrayObject $threadLocalStorage = null;
+	private static array $threadLocalStorage = [];
 
 	/** @phpstan-var ThreadSafeArray<int, string>|null */
 	private ?ThreadSafeArray $progressUpdates = null;
@@ -212,15 +212,6 @@ abstract class AsyncTask extends Runnable{
 	 * from.
 	 */
 	protected function storeLocal(string $key, mixed $complexData) : void{
-		if(self::$threadLocalStorage === null){
-			/*
-			 * It's necessary to use an object (not array) here because pthreads is stupid. Non-default array statics
-			 * will be inherited when task classes are copied to the worker thread, which would cause unwanted
-			 * inheritance of primitive thread-locals, which we really don't want for various reasons.
-			 * It won't try to inherit objects though, so this is the easiest solution.
-			 */
-			self::$threadLocalStorage = new \ArrayObject();
-		}
 		self::$threadLocalStorage[spl_object_id($this)][$key] = $complexData;
 	}
 
@@ -236,7 +227,7 @@ abstract class AsyncTask extends Runnable{
 	 */
 	protected function fetchLocal(string $key){
 		$id = spl_object_id($this);
-		if(self::$threadLocalStorage === null || !isset(self::$threadLocalStorage[$id][$key])){
+		if(!isset(self::$threadLocalStorage[$id][$key])){
 			throw new \InvalidArgumentException("No matching thread-local data found on this thread");
 		}
 
@@ -245,12 +236,7 @@ abstract class AsyncTask extends Runnable{
 
 	final public function __destruct(){
 		$this->reallyDestruct();
-		if(self::$threadLocalStorage !== null && isset(self::$threadLocalStorage[$h = spl_object_id($this)])){
-			unset(self::$threadLocalStorage[$h]);
-			if(self::$threadLocalStorage->count() === 0){
-				self::$threadLocalStorage = null;
-			}
-		}
+		unset(self::$threadLocalStorage[spl_object_id($this)]);
 	}
 
 	/**