diff --git a/src/pocketmine/level/format/io/region/Anvil.php b/src/pocketmine/level/format/io/region/Anvil.php
index c1aeccd03..272d89617 100644
--- a/src/pocketmine/level/format/io/region/Anvil.php
+++ b/src/pocketmine/level/format/io/region/Anvil.php
@@ -96,7 +96,7 @@ class Anvil extends McRegion{
 		]);
 	}
 
-	protected function nbtDeserialize(string $data){
+	protected function nbtDeserialize(string $data) : Chunk{
 		$nbt = new BigEndianNBTStream();
 		$chunk = $nbt->readCompressed($data);
 		if(!($chunk instanceof CompoundTag) or !$chunk->hasTag("Level")){
diff --git a/src/pocketmine/level/format/io/region/McRegion.php b/src/pocketmine/level/format/io/region/McRegion.php
index 88a47ce68..d935cc8a4 100644
--- a/src/pocketmine/level/format/io/region/McRegion.php
+++ b/src/pocketmine/level/format/io/region/McRegion.php
@@ -107,9 +107,9 @@ class McRegion extends BaseLevelProvider{
 	/**
 	 * @param string $data
 	 *
-	 * @return Chunk|null
+	 * @return Chunk
 	 */
-	protected function nbtDeserialize(string $data){
+	protected function nbtDeserialize(string $data) : Chunk{
 		$nbt = new BigEndianNBTStream();
 		$chunk = $nbt->readCompressed($data);
 		if(!($chunk instanceof CompoundTag) or !$chunk->hasTag("Level")){