diff --git a/nms-patches/ChunkRegionLoader.patch b/nms-patches/ChunkRegionLoader.patch
index b455a23971..50ae59b643 100644
--- a/nms-patches/ChunkRegionLoader.patch
+++ b/nms-patches/ChunkRegionLoader.patch
@@ -1,6 +1,11 @@
 --- a/net/minecraft/server/ChunkRegionLoader.java
 +++ b/net/minecraft/server/ChunkRegionLoader.java
-@@ -31,7 +31,7 @@
+@@ -27,11 +27,11 @@
+ public class ChunkRegionLoader implements IChunkLoader, IAsyncChunkSaver {
+ 
+     private static final Logger a = LogManager.getLogger();
+-    private final Map<ChunkCoordIntPair, NBTTagCompound> b = Maps.newHashMap();
++    private final Map<ChunkCoordIntPair, NBTTagCompound> b = java.util.Collections.synchronizedMap(Maps.newHashMap()); // CraftBukkit
      private final File c;
      private final DataFixer d;
      private PersistentStructureLegacy e;
@@ -165,7 +170,7 @@
              } else {
                  NBTTagCompound nbttagcompound1 = nbttagcompound.getCompound("Level");
  
-@@ -217,10 +289,14 @@
+@@ -217,10 +289,15 @@
      }
  
      public boolean a() {
@@ -175,6 +180,7 @@
 +    }
  
 +    private boolean processSaveQueueEntry(boolean logCompletion) {
++        synchronized (this.b) { // CraftBukkit
 +        Iterator iterator = this.b.entrySet().iterator();
          if (!iterator.hasNext()) {
 -            if (this.f) {
@@ -182,7 +188,7 @@
                  ChunkRegionLoader.a.info("ThreadedAnvilChunkStorage ({}): All chunks are saved", this.c.getName());
              }
  
-@@ -236,10 +312,14 @@
+@@ -236,10 +313,14 @@
                  return true;
              } else {
                  try {
@@ -198,7 +204,15 @@
                      if (this.e != null) {
                          this.e.a(chunkcoordintpair.a());
                      }
-@@ -266,15 +346,16 @@
+@@ -250,6 +331,7 @@
+                 return true;
+             }
+         }
++        } // CraftBukkit
+     }
+ 
+     private ChunkStatus.Type a(@Nullable NBTTagCompound nbttagcompound) {
+@@ -266,15 +348,16 @@
  
      public void b() {
          try {
@@ -218,7 +232,7 @@
          }
  
      }
-@@ -303,7 +384,7 @@
+@@ -303,7 +386,7 @@
  
          if (abiomebase != null) {
              for (int k = 0; k < abiomebase.length; ++k) {
@@ -227,7 +241,7 @@
              }
          }
  
-@@ -385,7 +466,7 @@
+@@ -385,7 +468,7 @@
          int[] aint = new int[abiomebase.length];
  
          for (int i = 0; i < abiomebase.length; ++i) {
@@ -236,7 +250,7 @@
          }
  
          nbttagcompound.setIntArray("Biomes", aint);
-@@ -487,27 +568,27 @@
+@@ -487,27 +570,27 @@
          }
  
          ChunkConverter chunkconverter = nbttagcompound.hasKeyOfType("UpgradeData", 10) ? new ChunkConverter(nbttagcompound.getCompound("UpgradeData")) : ChunkConverter.a;
@@ -270,7 +284,7 @@
          long i1 = nbttagcompound.getLong("InhabitedTime");
          Chunk chunk = new Chunk(generatoraccess.getMinecraftWorld(), i, j, abiomebase, chunkconverter, protochunkticklist, protochunkticklist1, i1);
  
-@@ -850,17 +931,29 @@
+@@ -850,17 +933,29 @@
      }
  
      @Nullable
@@ -302,7 +316,7 @@
          });
      }
  
-@@ -874,8 +967,14 @@
+@@ -874,8 +969,14 @@
          }
      }
  
@@ -318,7 +332,7 @@
              Iterator iterator = entity.bP().iterator();
  
              while (iterator.hasNext()) {
-@@ -891,7 +990,7 @@
+@@ -891,7 +992,7 @@
          boolean flag = false;
  
          try {