diff --git a/src/world/World.php b/src/world/World.php
index a65be12d3..36c495f63 100644
--- a/src/world/World.php
+++ b/src/world/World.php
@@ -2084,7 +2084,7 @@ class World implements ChunkManager{
 	/**
 	 * Gets the highest block Y value at a specific $x and $z
 	 *
-	 * @return int 0-255
+	 * @return int 0-255, or -1 if the column is empty
 	 * @throws WorldException if the terrain is not generated
 	 */
 	public function getHighestBlockAt(int $x, int $z) : int{