diff --git a/src/pocketmine/utils/BlockIterator.php b/src/pocketmine/utils/BlockIterator.php
index 64c48e2ed..9cbe30357 100644
--- a/src/pocketmine/utils/BlockIterator.php
+++ b/src/pocketmine/utils/BlockIterator.php
@@ -166,7 +166,7 @@ class BlockIterator implements \Iterator{
 		}
 
 		if(!$startBlockFound){
-			throw new \RuntimeException("Start block missed in BlockIterator");
+			throw new \InvalidStateException("Start block missed in BlockIterator");
 		}
 
 		$this->maxDistanceInt = round($maxDistance / (sqrt($mainDirection ** 2 + $secondDirection ** 2 + $thirdDirection ** 2) / $mainDirection));