diff --git a/src/pocketmine/block/Grass.php b/src/pocketmine/block/Grass.php
index bb6f63eb7..366cdf7e9 100644
--- a/src/pocketmine/block/Grass.php
+++ b/src/pocketmine/block/Grass.php
@@ -63,16 +63,20 @@ class Grass extends Solid{
 
 	public function onUpdate($type){
 		if($type === Level::BLOCK_UPDATE_RANDOM){
-			//TODO: light levels
-			$x = mt_rand($this->x - 1, $this->x + 1);
-			$y = mt_rand($this->y - 2, $this->y + 2);
-			$z = mt_rand($this->z - 1, $this->z + 1);
-			$block = $this->getLevel()->getBlock(new Vector3($x, $y, $z));
-			if($block->getId() === Block::DIRT){
-				if($block->getSide(1) instanceof Transparent){
-					Server::getInstance()->getPluginManager()->callEvent($ev = new BlockSpreadEvent($block, $this, new Grass()));
-					if(!$ev->isCancelled()){
-						$this->getLevel()->setBlock($block, $ev->getNewState());
+			$block = $this->getLevel()->getBlock(new Vector3($this->x, $this->y, $this->z));
+			if($block->getSide(1)->getLightLevel() < 4){
+				Server::getInstance()->getPluginManager()->callEvent($ev = new BlockSpreadEvent($block, $this, new Dirt()));
+			}elseif($block->getSide(1)->getLightLevel() >= 9){
+				for($l = 0; $l < 4; ++$l){
+					$x = mt_rand($this->x - 1, $this->x + 1);
+					$y = mt_rand($this->y - 2, $this->y + 2);
+					$z = mt_rand($this->z - 1, $this->z + 1);
+					$block = $this->getLevel()->getBlock(new Vector3($x, $y, $z));
+					if($block->getId() === Block::DIRT && $block->getDamage() === 0x0F && $block->getSide(1)->getLightLevel() >= 4 && $block->z <= 2){
+						Server::getInstance()->getPluginManager()->callEvent($ev = new BlockSpreadEvent($block, $this, new Grass()));
+						if(!$ev->isCancelled()){
+							$this->getLevel()->setBlock($block, $ev->getNewState());
+						}
 					}
 				}
 			}
@@ -99,4 +103,4 @@ class Grass extends Solid{
 
 		return false;
 	}
-}
\ No newline at end of file
+}