diff --git a/src/pocketmine/MemoryManager.php b/src/pocketmine/MemoryManager.php
index 0585ae77b..4208d5fb1 100644
--- a/src/pocketmine/MemoryManager.php
+++ b/src/pocketmine/MemoryManager.php
@@ -92,7 +92,7 @@ class MemoryManager{
 		$hardLimit = ((int) $this->server->getProperty("memory.main-hard-limit", $defaultMemory));
 
 		if($hardLimit <= 0){
-			ini_set("memory_limit", -1);
+			ini_set("memory_limit", '-1');
 		}else{
 			ini_set("memory_limit", $hardLimit . "M");
 		}
diff --git a/src/pocketmine/Server.php b/src/pocketmine/Server.php
index b2c37c22f..5b2ea05b1 100644
--- a/src/pocketmine/Server.php
+++ b/src/pocketmine/Server.php
@@ -1999,9 +1999,11 @@ class Server{
 			$this->getLogger()->debug("Removing event handlers");
 			HandlerList::unregisterAll();
 
-			$this->getLogger()->debug("Stopping all tasks");
-			$this->scheduler->cancelAllTasks();
-			$this->scheduler->mainThreadHeartbeat(PHP_INT_MAX);
+			if($this->scheduler instanceof ServerScheduler){
+				$this->getLogger()->debug("Stopping all tasks");
+				$this->scheduler->cancelAllTasks();
+				$this->scheduler->mainThreadHeartbeat(PHP_INT_MAX);
+			}
 
 			$this->getLogger()->debug("Saving properties");
 			$this->properties->save();
@@ -2010,10 +2012,12 @@ class Server{
 			$this->console->shutdown();
 			$this->console->notify();
 
-			$this->getLogger()->debug("Stopping network interfaces");
-			foreach($this->network->getInterfaces() as $interface){
-				$interface->shutdown();
-				$this->network->unregisterInterface($interface);
+			if($this->network instanceof Network){
+				$this->getLogger()->debug("Stopping network interfaces");
+				foreach($this->network->getInterfaces() as $interface){
+					$interface->shutdown();
+					$this->network->unregisterInterface($interface);
+				}
 			}
 
 			gc_collect_cycles();