diff --git a/bukkit/src/main/java/com/boydti/fawe/bukkit/wrapper/AsyncWorld.java b/bukkit/src/main/java/com/boydti/fawe/bukkit/wrapper/AsyncWorld.java
index 957c402b..c345dacd 100644
--- a/bukkit/src/main/java/com/boydti/fawe/bukkit/wrapper/AsyncWorld.java
+++ b/bukkit/src/main/java/com/boydti/fawe/bukkit/wrapper/AsyncWorld.java
@@ -121,9 +121,19 @@ public class AsyncWorld extends DelegateFaweQueue implements World, HasFaweQueue
     }
 
     public void changeWorld(World world, FaweQueue queue) {
-        flush();
         this.parent = world;
-        this.queue = queue;
+        if (queue != this.queue) {
+            if (this.queue != null) {
+                final FaweQueue oldQueue = this.queue;
+                TaskManager.IMP.async(new Runnable() {
+                    @Override
+                    public void run() {
+                        oldQueue.flush();
+                    }
+                });
+            }
+            this.queue = queue;
+        }
         setParent(queue);
     }
 
diff --git a/core/src/main/java/com/boydti/fawe/example/NMSRelighter.java b/core/src/main/java/com/boydti/fawe/example/NMSRelighter.java
index d4b6b8e8..17e52228 100644
--- a/core/src/main/java/com/boydti/fawe/example/NMSRelighter.java
+++ b/core/src/main/java/com/boydti/fawe/example/NMSRelighter.java
@@ -196,7 +196,7 @@ public class NMSRelighter implements Relighter{
         Map<Integer, Object> currentMap = lightQueue.get(index);
         if (currentMap == null) {
             currentMap = new Int2ObjectOpenHashMap<>();
-            synchronized (lightQueue) {
+            synchronized (this) {
                 this.lightQueue.put(index, currentMap);
             }
         }
diff --git a/core/src/main/java/com/boydti/fawe/example/WeakFaweQueueMap.java b/core/src/main/java/com/boydti/fawe/example/WeakFaweQueueMap.java
index f03fa23d..45e48644 100644
--- a/core/src/main/java/com/boydti/fawe/example/WeakFaweQueueMap.java
+++ b/core/src/main/java/com/boydti/fawe/example/WeakFaweQueueMap.java
@@ -33,7 +33,7 @@ public class WeakFaweQueueMap implements IFaweQueueMap {
         public Reference<FaweChunk> put(long key, Reference<FaweChunk> value) {
             if (parent.getProgressTask() != null) {
                 try {
-                    parent.getProgressTask().run(FaweQueue.ProgressType.QUEUE, size() + 1);
+                    parent.getProgressTask().run(FaweQueue.ProgressType.QUEUE, size());
                 } catch (Throwable e) {
                     e.printStackTrace();
                 }