diff --git a/src/main/java/com/gmail/nossr50/listeners/WorldListener.java b/src/main/java/com/gmail/nossr50/listeners/WorldListener.java
index 5c6d36551..7e741c6de 100644
--- a/src/main/java/com/gmail/nossr50/listeners/WorldListener.java
+++ b/src/main/java/com/gmail/nossr50/listeners/WorldListener.java
@@ -71,7 +71,7 @@ public class WorldListener implements Listener {
 
         manager.loadChunk(cx, cz, world);
 
-        for(int y = 0; y < 4; y++) {
+        for(int y = 0; y < (world.getMaxHeight() / 64); y++) {
             String chunkletName = world.getName() + "," + cx + "," + cz + "," + y;
 	    ChunkletStore tempChunklet = manager.store.get(chunkletName);
             PrimitiveChunkletStore primitiveChunklet = null;
@@ -120,6 +120,10 @@ public class WorldListener implements Listener {
                         else
                             return;
                         boolean[] newArray = cChunk.store[x][z];
+                        if(oldArray.length < 64)
+                            return;
+                        else if(newArray.length < ((y * 64) + 64))
+                            return;
                         System.arraycopy(oldArray, 0, newArray, (y * 64), 64);
                     }
                 }
diff --git a/src/main/java/com/gmail/nossr50/runnables/BlockStoreConversionZDirectory.java b/src/main/java/com/gmail/nossr50/runnables/BlockStoreConversionZDirectory.java
index e201c4abb..ad528b03f 100755
--- a/src/main/java/com/gmail/nossr50/runnables/BlockStoreConversionZDirectory.java
+++ b/src/main/java/com/gmail/nossr50/runnables/BlockStoreConversionZDirectory.java
@@ -82,7 +82,7 @@ public class BlockStoreConversionZDirectory implements Runnable {
 
         this.manager.loadChunk(this.cx, this.cz, this.world);
 
-        for(this.y = 0; this.y < 4; this.y++) {
+        for(this.y = 0; this.y < (this.world.getMaxHeight() / 64); this.y++) {
             this.chunkletName = this.world.getName() + "," + this.cx + "," + this.cz + "," + this.y;
 	    this.tempChunklet = this.manager.store.get(this.chunkletName);
             if(this.tempChunklet instanceof PrimitiveChunkletStore)
@@ -128,6 +128,10 @@ public class BlockStoreConversionZDirectory implements Runnable {
                         else
                             return;
                         this.newArray = this.currentChunk.store[x][z];
+                        if(this.oldArray.length < 64)
+                            return;
+                        else if(this.newArray.length < ((this.y * 64) + 64))
+                            return;
                         System.arraycopy(this.oldArray, 0, this.newArray, (this.y * 64), 64);
                     }
                 }