diff --git a/src/world/format/io/region/Anvil.php b/src/world/format/io/region/Anvil.php
index 1bd9450f81..88951c92bf 100644
--- a/src/world/format/io/region/Anvil.php
+++ b/src/world/format/io/region/Anvil.php
@@ -36,7 +36,10 @@ class Anvil extends RegionWorldProvider{
 	}
 
 	protected function deserializeSubChunk(CompoundTag $subChunk) : SubChunk{
-		return new SubChunk(BlockLegacyIds::AIR << 4, [SubChunkConverter::convertSubChunkYZX($subChunk->getByteArray("Blocks"), $subChunk->getByteArray("Data"))]);
+		return new SubChunk(BlockLegacyIds::AIR << 4, [SubChunkConverter::convertSubChunkYZX(
+			self::readFixedSizeByteArray($subChunk, "Blocks", 4096),
+			self::readFixedSizeByteArray($subChunk, "Data", 2048)
+		)]);
 		//ignore legacy light information
 	}
 
diff --git a/src/world/format/io/region/McRegion.php b/src/world/format/io/region/McRegion.php
index 6f5ce48824..78288b6993 100644
--- a/src/world/format/io/region/McRegion.php
+++ b/src/world/format/io/region/McRegion.php
@@ -36,7 +36,6 @@ use pocketmine\world\format\io\ChunkUtils;
 use pocketmine\world\format\io\exception\CorruptedChunkException;
 use pocketmine\world\format\io\SubChunkConverter;
 use pocketmine\world\format\SubChunk;
-use function str_repeat;
 use function zlib_decode;
 
 class McRegion extends RegionWorldProvider{
@@ -68,8 +67,8 @@ class McRegion extends RegionWorldProvider{
 		}
 
 		$subChunks = [];
-		$fullIds = ($fullIdsTag = $chunk->getTag("Blocks")) instanceof ByteArrayTag ? $fullIdsTag->getValue() : str_repeat("\x00", 32768);
-		$fullData = ($fullDataTag = $chunk->getTag("Data")) instanceof ByteArrayTag ? $fullDataTag->getValue() : str_repeat("\x00", 16384);
+		$fullIds = self::readFixedSizeByteArray($chunk, "Blocks", 32768);
+		$fullData = self::readFixedSizeByteArray($chunk, "Data", 16384);
 
 		for($y = 0; $y < 8; ++$y){
 			$subChunks[$y] = new SubChunk(BlockLegacyIds::AIR << 4, [SubChunkConverter::convertSubChunkFromLegacyColumn($fullIds, $fullData, $y)]);
diff --git a/src/world/format/io/region/PMAnvil.php b/src/world/format/io/region/PMAnvil.php
index 557026a9d3..960dd53691 100644
--- a/src/world/format/io/region/PMAnvil.php
+++ b/src/world/format/io/region/PMAnvil.php
@@ -36,7 +36,10 @@ class PMAnvil extends RegionWorldProvider{
 	use LegacyAnvilChunkTrait;
 
 	protected function deserializeSubChunk(CompoundTag $subChunk) : SubChunk{
-		return new SubChunk(BlockLegacyIds::AIR << 4, [SubChunkConverter::convertSubChunkXZY($subChunk->getByteArray("Blocks"), $subChunk->getByteArray("Data"))]);
+		return new SubChunk(BlockLegacyIds::AIR << 4, [SubChunkConverter::convertSubChunkXZY(
+			self::readFixedSizeByteArray($subChunk, "Blocks", 4096),
+			self::readFixedSizeByteArray($subChunk, "Data", 2048)
+		)]);
 	}
 
 	protected static function getRegionFileExtension() : string{
diff --git a/src/world/format/io/region/RegionWorldProvider.php b/src/world/format/io/region/RegionWorldProvider.php
index 06c259f371..fa2162fe11 100644
--- a/src/world/format/io/region/RegionWorldProvider.php
+++ b/src/world/format/io/region/RegionWorldProvider.php
@@ -24,6 +24,7 @@ declare(strict_types=1);
 namespace pocketmine\world\format\io\region;
 
 use pocketmine\nbt\NBT;
+use pocketmine\nbt\tag\ByteArrayTag;
 use pocketmine\nbt\tag\CompoundTag;
 use pocketmine\nbt\tag\ListTag;
 use pocketmine\utils\Utils;
@@ -41,6 +42,7 @@ use function mkdir;
 use function morton2d_encode;
 use function rename;
 use function scandir;
+use function strlen;
 use function strrpos;
 use function substr;
 use function time;
@@ -196,6 +198,18 @@ abstract class RegionWorldProvider extends BaseWorldProvider{
 		return $result;
 	}
 
+	protected static function readFixedSizeByteArray(CompoundTag $chunk, string $tagName, int $length) : string{
+		$tag = $chunk->getTag($tagName);
+		if(!($tag instanceof ByteArrayTag)){
+			throw new CorruptedChunkException("Expected TAG_ByteArray for '$tagName'");
+		}
+		$data = $tag->getValue();
+		if(strlen($data) !== $length){
+			throw new CorruptedChunkException("Expected '$tagName' payload to have exactly $length bytes, but have " . strlen($data));
+		}
+		return $data;
+	}
+
 	/**
 	 * @throws CorruptedChunkException
 	 */