diff --git a/src/pocketmine/level/generator/Flat.php b/src/pocketmine/level/generator/Flat.php
index 5285bd620..904dedba9 100644
--- a/src/pocketmine/level/generator/Flat.php
+++ b/src/pocketmine/level/generator/Flat.php
@@ -118,8 +118,18 @@ class Flat extends Generator{
 		for($Z = 0; $Z < 16; ++$Z){
 			for($X = 0; $X < 16; ++$X){
 				$this->chunk->setBiomeId($X, $Z, $biome);
-				for($y = 0; $y < 256 and isset($this->structure[$y]); ++$y){
-					$this->chunk->setBlock($X, $y, $Z, ...$this->structure[$y]);
+			}
+		}
+
+		for($sy = 0; $sy < 256; $sy += 16){
+			$subchunk = $this->chunk->getSubChunk($sy >> 4, true);
+			for($y = 0; $y < 16 and isset($this->structure[$y | $sy]); ++$y){
+				list($id, $meta) = $this->structure[$y | $sy];
+
+				for($Z = 0; $Z < 16; ++$Z){
+					for($X = 0; $X < 16; ++$X){
+						$subchunk->setBlock($X, $y, $Z, $id, $meta);
+					}
 				}
 			}
 		}