diff --git a/src/SharpCompress/Archives/Rar/RarArchive.cs b/src/SharpCompress/Archives/Rar/RarArchive.cs
index ab341e0c..699073cb 100644
--- a/src/SharpCompress/Archives/Rar/RarArchive.cs
+++ b/src/SharpCompress/Archives/Rar/RarArchive.cs
@@ -24,7 +24,11 @@ namespace SharpCompress.Archives.Rar
         internal RarArchive(FileInfo fileInfo, ReaderOptions options)
             : base(ArchiveType.Rar, fileInfo, options)
         {
+#if !RarV2017_USELEGACY
+            Unpack = new SharpCompress.Compressors.Rar.UnpackV2017.Unpack();
+#else
             Unpack = new SharpCompress.Compressors.Rar.UnpackV1.Unpack();
+#endif
         }
 
         protected override IEnumerable<RarVolume> LoadVolumes(FileInfo file)
@@ -41,7 +45,11 @@ namespace SharpCompress.Archives.Rar
         internal RarArchive(IEnumerable<Stream> streams, ReaderOptions options)
             : base(ArchiveType.Rar, streams, options)
         {
+#if !RarV2017_USELEGACY
+            Unpack = new SharpCompress.Compressors.Rar.UnpackV2017.Unpack();
+#else
             Unpack = new SharpCompress.Compressors.Rar.UnpackV1.Unpack();
+#endif
         }
 
         protected override IEnumerable<RarArchiveEntry> LoadEntries(IEnumerable<RarVolume> volumes)
diff --git a/src/SharpCompress/Compressors/Rar/UnpackV2017/FragmentedWindow.unpack50frag_cpp.cs b/src/SharpCompress/Compressors/Rar/UnpackV2017/FragmentedWindow.unpack50frag_cpp.cs
index ca1b78df..8d4dab7a 100644
--- a/src/SharpCompress/Compressors/Rar/UnpackV2017/FragmentedWindow.unpack50frag_cpp.cs
+++ b/src/SharpCompress/Compressors/Rar/UnpackV2017/FragmentedWindow.unpack50frag_cpp.cs
@@ -112,6 +112,21 @@ set {
 }
 }
 
+// sharpcompress: added the following code
+public void GetBuffer(size_t Item, out byte[] buf, out uint offset) {
+  if (Item<MemSize[0]) {
+    //return Mem[0][Item];
+    buf = Mem[0]; offset = Item; return;
+  }
+  for (uint I=1;I<MemSize.Length;I++) {
+    if (Item<MemSize[I]) {
+      //return Mem[I][Item-MemSize[I-1]];
+      buf = Mem[I]; offset = Item-MemSize[I-1]; return;
+    }
+  }
+  //return Mem[0][0]; // Must never happen;
+  buf = Mem[0]; offset = 0; return; // Must never happen;
+}
 
 public void CopyString(uint Length,uint Distance,ref size_t UnpPtr,size_t MaxWinMask)
 {
diff --git a/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.cs b/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.cs
index 54c877e7..6fbf86c0 100644
--- a/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.cs
+++ b/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.cs
@@ -24,7 +24,6 @@ namespace SharpCompress.Compressors.Rar.UnpackV2017
         private Stream writeStream;
 
         private void _UnpackCtor() {
-            BlockTables.Init();
             for (int i = 0; i < this.AudV.Length; i++) {
                 this.AudV[i] = new AudioVariables();
             }
diff --git a/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.unpack50_cpp.cs b/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.unpack50_cpp.cs
index 4cf75009..d39dbb98 100644
--- a/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.unpack50_cpp.cs
+++ b/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.unpack50_cpp.cs
@@ -404,7 +404,8 @@ void UnpWriteBuf()
       EmptyCount++;
   }
   if (EmptyCount>0)
-    Filters.Alloc(Filters.Count-EmptyCount);
+    //Filters.Alloc(Filters.Count-EmptyCount);
+    throw new NotImplementedException();
 
   if (!NotAllFiltersProcessed) // Only if all filters are processed.
   {
@@ -428,6 +429,8 @@ void UnpWriteBuf()
 
 byte[] ApplyFilter(byte[] Data,uint DataSize,UnpackFilter Flt)
 {
+            throw new NotImplementedException();
+#if false
   byte[] SrcData=Data;
   switch(Flt.Type)
   {
@@ -509,6 +512,7 @@ byte[] ApplyFilter(byte[] Data,uint DataSize,UnpackFilter Flt)
 
   }
   return null;
+#endif
 }
 
 
@@ -525,7 +529,9 @@ void UnpWriteArea(size_t StartPtr,size_t EndPtr)
     while (SizeToWrite>0)
     {
       size_t BlockSize=FragWindow.GetBlockSize(StartPtr,SizeToWrite);
-      UnpWriteData(&FragWindow[StartPtr],BlockSize);
+      //UnpWriteData(&FragWindow[StartPtr],BlockSize);
+      FragWindow.GetBuffer(StartPtr, out var __buffer, out var __offset);
+      UnpWriteData(__buffer, __offset, BlockSize);
       SizeToWrite-=BlockSize;
       StartPtr=(StartPtr+BlockSize) & MaxWinMask;
     }
diff --git a/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.unpack_cpp.cs b/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.unpack_cpp.cs
index 619974c2..502763ad 100644
--- a/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.unpack_cpp.cs
+++ b/src/SharpCompress/Compressors/Rar/UnpackV2017/Unpack.unpack_cpp.cs
@@ -205,6 +205,8 @@ void UnpInitData(bool Solid)
 //    memset(Window,0,MaxWinSize);
     //memset(&BlockTables,0,sizeof(BlockTables));
     BlockTables = new UnpackBlockTables();
+    // sharpcompress: no default ctor for struct
+    BlockTables.Init();
     UnpPtr=WrPtr=0;
     WriteBorder=Math.Min(MaxWinSize,UNPACK_MAX_WRITE)&MaxWinMask;
   }
diff --git a/src/SharpCompress/Readers/Rar/RarReader.cs b/src/SharpCompress/Readers/Rar/RarReader.cs
index 20afa5e1..71fe260c 100644
--- a/src/SharpCompress/Readers/Rar/RarReader.cs
+++ b/src/SharpCompress/Readers/Rar/RarReader.cs
@@ -18,7 +18,11 @@ namespace SharpCompress.Readers.Rar
         internal RarReader(ReaderOptions options)
             : base(options, ArchiveType.Rar)
         {
+#if !RarV2017_USELEGACY
+            this.pack = new SharpCompress.Compressors.Rar.UnpackV2017.Unpack();
+#else
             this.pack = new SharpCompress.Compressors.Rar.UnpackV1.Unpack();
+#endif
         }
 
         internal abstract void ValidateArchive(RarVolume archive);