diff --git a/src/pocketmine/level/generator/Flat.php b/src/pocketmine/level/generator/Flat.php
index 2264c1ea8..edaf7cb19 100644
--- a/src/pocketmine/level/generator/Flat.php
+++ b/src/pocketmine/level/generator/Flat.php
@@ -107,7 +107,7 @@ class Flat extends Generator{
 		}
 
 
-		$this->chunk = $this->level->getChunk($chunkX, $chunkZ);
+		$this->chunk = clone $this->level->getChunk($chunkX, $chunkZ);
 		$this->chunk->setGenerated();
 
 		for($Z = 0; $Z < 16; ++$Z){