diff --git a/src/pocketmine/Server.php b/src/pocketmine/Server.php
index bb9bd2f5e..0203e1a8e 100644
--- a/src/pocketmine/Server.php
+++ b/src/pocketmine/Server.php
@@ -2352,7 +2352,11 @@ class Server{
 		}
 
 		//Do level ticks
-		foreach($this->getLevels() as $level){
+		foreach($this->levels as $k => $level){
+			if(!isset($this->levels[$k])){
+				// Level unloaded during the tick of a level earlier in this loop, perhaps by plugin
+				continue;
+			}
 			if($level->getTickRate() > $this->baseTickRate and --$level->tickRateCounter > 0){
 				continue;
 			}