diff --git a/src/SharpCompress/Compressors/Xz/XZHeader.cs b/src/SharpCompress/Compressors/Xz/XZHeader.cs
index a5ed8c4ac..9a0b70d62 100644
--- a/src/SharpCompress/Compressors/Xz/XZHeader.cs
+++ b/src/SharpCompress/Compressors/Xz/XZHeader.cs
@@ -11,7 +11,7 @@ public class XZHeader
     private readonly byte[] MagicHeader = { 0xFD, 0x37, 0x7A, 0x58, 0x5a, 0x00 };
 
     public CheckType BlockCheckType { get; private set; }
-    public int BlockCheckSize => ((((int)BlockCheckType) + 2) / 3) * 4;
+    public int BlockCheckSize => 4 << ((((int)BlockCheckType + 2) / 3) - 1);
 
     public XZHeader(BinaryReader reader) => _reader = reader;
 
diff --git a/src/SharpCompress/Compressors/Xz/XZStream.cs b/src/SharpCompress/Compressors/Xz/XZStream.cs
index 26d3dcb2e..8971e9f58 100644
--- a/src/SharpCompress/Compressors/Xz/XZStream.cs
+++ b/src/SharpCompress/Compressors/Xz/XZStream.cs
@@ -25,13 +25,10 @@ private void AssertBlockCheckTypeIsSupported()
         switch (Header.BlockCheckType)
         {
             case CheckType.NONE:
-                break;
             case CheckType.CRC32:
-                break;
             case CheckType.CRC64:
-                break;
             case CheckType.SHA256:
-                throw new NotImplementedException();
+                break;
             default:
                 throw new NotSupportedException("Check Type unknown to this version of decoder.");
         }