diff --git a/src/pocketmine/level/Level.php b/src/pocketmine/level/Level.php
index 1c1b221cd..a98a07581 100644
--- a/src/pocketmine/level/Level.php
+++ b/src/pocketmine/level/Level.php
@@ -1426,7 +1426,7 @@ class Level implements ChunkManager, Metadatable{
 				$this->skyLightUpdate->setAndUpdateLight($x, $i, $z, 15);
 			}
 		}else{ //No heightmap change, block changed "underground"
-			$this->skyLightUpdate->setAndUpdateLight($x, $y, $z, max(0, $this->getHighestAdjacentBlockSkyLight($x, $y, $z) - BlockFactory::$lightFilter[$sourceId]));
+			$this->skyLightUpdate->setAndUpdateLight($x, $y, $z, max(0, $this->getHighestAdjacentBlockSkyLight($x, $y, $z) - BlockFactory::$lightFilter[$source->getId()]));
 		}
 
 		$this->timings->doBlockSkyLightUpdates->stopTiming();