diff --git a/BauSystem_Main/src/de/steamwar/bausystem/features/simulator2/SimulatorWatcher.java b/BauSystem_Main/src/de/steamwar/bausystem/features/simulator2/SimulatorWatcher.java
index 5c1e8ddb..8bc0d8c6 100644
--- a/BauSystem_Main/src/de/steamwar/bausystem/features/simulator2/SimulatorWatcher.java
+++ b/BauSystem_Main/src/de/steamwar/bausystem/features/simulator2/SimulatorWatcher.java
@@ -58,8 +58,10 @@ public class SimulatorWatcher {
 
     public void update(Simulator simulator) {
         REntityServer rEntityServer = entityServers.get(simulator);
-        rEntityServer.getEntities().forEach(REntity::die);
-        createSim(rEntityServer, simulator);
+        if (rEntityServer != null) {
+            rEntityServer.getEntities().forEach(REntity::die);
+            createSim(rEntityServer, simulator);
+        }
 
         new ArrayList<>(watchers.values()).forEach(simulatorRunnablePair -> {
             if (simulatorRunnablePair.getKey() == simulator) {