diff --git a/src/pocketmine/level/Level.php b/src/pocketmine/level/Level.php
index 2b7e024b6..66802a15d 100644
--- a/src/pocketmine/level/Level.php
+++ b/src/pocketmine/level/Level.php
@@ -2296,28 +2296,33 @@ class Level implements ChunkManager, Metadatable{
 		return $result;
 	}
 
-	public function generateChunkCallback(int $x, int $z, Chunk $chunk){
+	public function generateChunkCallback(int $x, int $z, ?Chunk $chunk){
 		Timings::$generationCallbackTimer->startTiming();
 		if(isset($this->chunkPopulationQueue[$index = Level::chunkHash($x, $z)])){
-			$oldChunk = $this->getChunk($x, $z, false);
 			for($xx = -1; $xx <= 1; ++$xx){
 				for($zz = -1; $zz <= 1; ++$zz){
 					unset($this->chunkPopulationLock[Level::chunkHash($x + $xx, $z + $zz)]);
 				}
 			}
 			unset($this->chunkPopulationQueue[$index]);
-			$this->setChunk($x, $z, $chunk, false);
-			if(($oldChunk === null or !$oldChunk->isPopulated()) and $chunk->isPopulated()){
-				$this->server->getPluginManager()->callEvent(new ChunkPopulateEvent($this, $chunk));
 
-				foreach($this->getChunkLoaders($x, $z) as $loader){
-					$loader->onChunkPopulated($chunk);
+			if($chunk !== null){
+				$oldChunk = $this->getChunk($x, $z, false);
+				$this->setChunk($x, $z, $chunk, false);
+				if(($oldChunk === null or !$oldChunk->isPopulated()) and $chunk->isPopulated()){
+					$this->server->getPluginManager()->callEvent(new ChunkPopulateEvent($this, $chunk));
+
+					foreach($this->getChunkLoaders($x, $z) as $loader){
+						$loader->onChunkPopulated($chunk);
+					}
 				}
 			}
 		}elseif(isset($this->chunkPopulationLock[$index])){
 			unset($this->chunkPopulationLock[$index]);
-			$this->setChunk($x, $z, $chunk, false);
-		}else{
+			if($chunk !== null){
+				$this->setChunk($x, $z, $chunk, false);
+			}
+		}elseif($chunk !== null){
 			$this->setChunk($x, $z, $chunk, false);
 		}
 		Timings::$generationCallbackTimer->stopTiming();
diff --git a/src/pocketmine/level/generator/PopulationTask.php b/src/pocketmine/level/generator/PopulationTask.php
index 76f267784..6af27bb38 100644
--- a/src/pocketmine/level/generator/PopulationTask.php
+++ b/src/pocketmine/level/generator/PopulationTask.php
@@ -152,11 +152,11 @@ class PopulationTask extends AsyncTask{
 				$c = $this->{"chunk$i"};
 				if($c !== null){
 					$c = Chunk::fastDeserialize($c);
-					$level->generateChunkCallback($c->getX(), $c->getZ(), $c);
+					$level->generateChunkCallback($c->getX(), $c->getZ(), $this->state ? $c : null);
 				}
 			}
 
-			$level->generateChunkCallback($chunk->getX(), $chunk->getZ(), $chunk);
+			$level->generateChunkCallback($chunk->getX(), $chunk->getZ(), $this->state ? $chunk : null);
 		}
 	}
 }