diff --git a/src/main/java/com/reandroid/lib/arsc/chunk/BaseChunk.java b/src/main/java/com/reandroid/lib/arsc/chunk/BaseChunk.java
index 1b2f139..344ab36 100755
--- a/src/main/java/com/reandroid/lib/arsc/chunk/BaseChunk.java
+++ b/src/main/java/com/reandroid/lib/arsc/chunk/BaseChunk.java
@@ -35,6 +35,9 @@ public abstract class BaseChunk extends ExpandableBlockContainer {
     protected void addToHeader(Block block){
         mHeaderBlock.addChild(block);
     }
+    void setHeaderLoaded(HeaderBlock.HeaderLoaded headerLoaded){
+        mHeaderBlock.setHeaderLoaded(headerLoaded);
+    }
     public HeaderBlock getHeaderBlock(){
         return mHeaderBlock;
     }
@@ -50,16 +53,21 @@ public abstract class BaseChunk extends ExpandableBlockContainer {
     @Override
     public void onReadBytes(BlockReader reader) throws IOException {
         HeaderBlock headerBlock=reader.readHeaderBlock();
-        ChunkType chunkType = headerBlock.getChunkType();
-        if(chunkType==null || chunkType==ChunkType.NULL){
-            throw new IOException("Invalid chunk: "+headerBlock);
-        }
-        BlockReader chunkReader=reader.create(reader.getPosition(), headerBlock.getChunkSize());
+        checkInvalidChunk(headerBlock);
+        BlockReader chunkReader = reader.create(
+                reader.getPosition(),
+                headerBlock.getChunkSize());
         super.onReadBytes(chunkReader);
         reader.offset(headerBlock.getChunkSize());
         chunkReader.close();
         onChunkLoaded();
     }
+    void checkInvalidChunk(HeaderBlock headerBlock) throws IOException {
+        ChunkType chunkType = headerBlock.getChunkType();
+        if(chunkType==null || chunkType==ChunkType.NULL){
+            throw new IOException("Invalid chunk: "+headerBlock);
+        }
+    }
     @Override
     public String toString(){
         StringBuilder builder=new StringBuilder();
diff --git a/src/main/java/com/reandroid/lib/arsc/chunk/PackageBlock.java b/src/main/java/com/reandroid/lib/arsc/chunk/PackageBlock.java
index 80e9062..d1380ad 100755
--- a/src/main/java/com/reandroid/lib/arsc/chunk/PackageBlock.java
+++ b/src/main/java/com/reandroid/lib/arsc/chunk/PackageBlock.java
@@ -115,6 +115,9 @@ package com.reandroid.lib.arsc.chunk;
         addChild(mPackageLastBlocks);
 
     }
+    public BlockList<UnknownChunk> getUnknownChunkList(){
+         return mPackageLastBlocks.getUnknownChunkList();
+    }
 
     public StagedAliasEntry searchByStagedResId(int stagedResId){
         for(StagedAlias stagedAlias:getStagedAliasList().getChildes()){
diff --git a/src/main/java/com/reandroid/lib/arsc/container/PackageLastBlocks.java b/src/main/java/com/reandroid/lib/arsc/container/PackageLastBlocks.java
index d644ea0..53acf24 100755
--- a/src/main/java/com/reandroid/lib/arsc/container/PackageLastBlocks.java
+++ b/src/main/java/com/reandroid/lib/arsc/container/PackageLastBlocks.java
@@ -29,22 +29,30 @@ public class PackageLastBlocks extends FixedBlockContainer {
     private final BlockList<StagedAlias> mStagedAliasList;
     private final BlockList<Overlayable> mOverlayableList;
     private final BlockList<OverlayablePolicy> mOverlayablePolicyList;
+    private final BlockList<UnknownChunk> mUnknownChunkList;
     public PackageLastBlocks(SpecTypePairArray specTypePairArray,
                              LibraryBlock libraryBlock,
                              BlockList<StagedAlias> stagedAliasList,
                              BlockList<Overlayable> overlayableList,
                              BlockList<OverlayablePolicy> overlayablePolicyList){
-        super(5);
+        super(6);
         this.mSpecTypePairArray=specTypePairArray;
         this.mLibraryBlock=libraryBlock;
         this.mStagedAliasList=stagedAliasList;
         this.mOverlayableList=overlayableList;
         this.mOverlayablePolicyList=overlayablePolicyList;
+
+        this.mUnknownChunkList = new BlockList<>();
+
         addChild(0, mSpecTypePairArray);
         addChild(1, mLibraryBlock);
         addChild(2, mStagedAliasList);
         addChild(3, mOverlayableList);
         addChild(4, mOverlayablePolicyList);
+        addChild(5, mUnknownChunkList);
+    }
+    public BlockList<UnknownChunk> getUnknownChunkList(){
+        return mUnknownChunkList;
     }
 
     @Override
@@ -72,7 +80,7 @@ public class PackageLastBlocks extends FixedBlockContainer {
         }else if(chunkType==ChunkType.STAGED_ALIAS){
             readStagedAlias(reader);
         }else {
-            readUnexpectedBlock(reader, headerBlock);
+            readUnknownChunk(reader);
         }
         return pos!=reader.getPosition();
     }
@@ -100,7 +108,9 @@ public class PackageLastBlocks extends FixedBlockContainer {
         overlayablePolicy.readBytes(reader);
         mOverlayablePolicyList.add(overlayablePolicy);
     }
-    private void readUnexpectedBlock(BlockReader reader, HeaderBlock headerBlock) throws IOException{
-        throw new IOException(reader.getActualPosition()+", Unexpected block: "+headerBlock.toString());
+    private void readUnknownChunk(BlockReader reader) throws IOException{
+        UnknownChunk unknownChunk = new UnknownChunk();
+        unknownChunk.readBytes(reader);
+        mUnknownChunkList.add(unknownChunk);
     }
 }
diff --git a/src/main/java/com/reandroid/lib/arsc/header/HeaderBlock.java b/src/main/java/com/reandroid/lib/arsc/header/HeaderBlock.java
index 00b31a4..b410b72 100755
--- a/src/main/java/com/reandroid/lib/arsc/header/HeaderBlock.java
+++ b/src/main/java/com/reandroid/lib/arsc/header/HeaderBlock.java
@@ -18,13 +18,18 @@ package com.reandroid.lib.arsc.header;
 import com.reandroid.lib.arsc.chunk.ChunkType;
 import com.reandroid.lib.arsc.base.Block;
 import com.reandroid.lib.arsc.container.ExpandableBlockContainer;
+import com.reandroid.lib.arsc.io.BlockLoad;
+import com.reandroid.lib.arsc.io.BlockReader;
 import com.reandroid.lib.arsc.item.IntegerItem;
 import com.reandroid.lib.arsc.item.ShortItem;
 
-public class HeaderBlock extends ExpandableBlockContainer {
+import java.io.IOException;
+
+ public class HeaderBlock extends ExpandableBlockContainer implements BlockLoad {
     private final ShortItem mType;
     private final ShortItem mHeaderSize;
     private final IntegerItem mChunkSize;
+    private HeaderLoaded mHeaderLoaded;
     public HeaderBlock(short type){
         super(3);
         this.mType=new ShortItem(type);
@@ -33,6 +38,12 @@ public class HeaderBlock extends ExpandableBlockContainer {
         addChild(mType);
         addChild(mHeaderSize);
         addChild(mChunkSize);
+        this.mType.setBlockLoad(this);
+        this.mHeaderSize.setBlockLoad(this);
+        this.mChunkSize.setBlockLoad(this);
+    }
+    public void setHeaderLoaded(HeaderLoaded headerLoaded){
+        this.mHeaderLoaded=headerLoaded;
     }
     public ChunkType getChunkType(){
         return ChunkType.get(mType.get());
@@ -54,7 +65,7 @@ public class HeaderBlock extends ExpandableBlockContainer {
     }
 
     public int getHeaderSize(){
-        return (0xffff & mHeaderSize.get());
+        return mHeaderSize.unsignedInt();
     }
     public void setHeaderSize(short headerSize){
         mHeaderSize.set(headerSize);
@@ -82,6 +93,21 @@ public class HeaderBlock extends ExpandableBlockContainer {
         int count=parent.countBytes();
         setChunkSize(count);
     }
+    @Override
+    public void onBlockLoaded(BlockReader reader, Block sender) throws IOException {
+        HeaderLoaded headerLoaded = mHeaderLoaded;
+        if(headerLoaded==null){
+            return;
+        }
+        if(sender==this.mType){
+            headerLoaded.onChunkTypeLoaded(mType.get());
+        }else if(sender==this.mHeaderSize){
+            headerLoaded.onHeaderSizeLoaded(mHeaderSize.unsignedInt());
+        }else if(sender==this.mChunkSize){
+            headerLoaded.onChunkSizeLoaded(mHeaderSize.unsignedInt(),
+                    mChunkSize.get());
+        }
+    }
 
     @Override
     protected void onRefreshed() {
@@ -110,4 +136,10 @@ public class HeaderBlock extends ExpandableBlockContainer {
         builder.append("}");
         return builder.toString();
     }
+
+    public interface HeaderLoaded{
+        void onChunkTypeLoaded(short type);
+        void onHeaderSizeLoaded(int headerSize);
+        void onChunkSizeLoaded(int headerSize, int chunkSize);
+    }
 }
diff --git a/src/main/java/com/reandroid/lib/arsc/item/ShortItem.java b/src/main/java/com/reandroid/lib/arsc/item/ShortItem.java
index faf83aa..a6c8d48 100755
--- a/src/main/java/com/reandroid/lib/arsc/item/ShortItem.java
+++ b/src/main/java/com/reandroid/lib/arsc/item/ShortItem.java
@@ -37,6 +37,9 @@ public class ShortItem extends BlockItem {
     public short get(){
         return mCache;
     }
+    public int unsignedInt(){
+        return 0xffff & get();
+    }
     @Override
     protected void onBytesChanged() {
         // To save cpu usage, better to calculate once only when bytes changed