diff --git a/LZ/Decompressor.cs b/LZ/Decompressor.cs
index a256ef0..1d7759a 100644
--- a/LZ/Decompressor.cs
+++ b/LZ/Decompressor.cs
@@ -91,7 +91,7 @@ namespace SabreTools.Compression.LZ
             string inputExtension = Path.GetExtension(input).TrimStart('.');
 
             // If we have no extension
-            if (string.IsNullOrWhiteSpace(inputExtension))
+            if (string.IsNullOrEmpty(inputExtension))
                 return Path.GetFileNameWithoutExtension(input);
 
             // If we have an extension of length 1
@@ -552,6 +552,6 @@ namespace SabreTools.Compression.LZ
             return fileHeader;
         }
 
-        #endregion
+#endregion
     }
 }
\ No newline at end of file
diff --git a/OldDotNet.cs b/OldDotNet.cs
new file mode 100644
index 0000000..65831ad
--- /dev/null
+++ b/OldDotNet.cs
@@ -0,0 +1,50 @@
+#if NET20 || NET35
+
+using System;
+using System.IO;
+
+namespace SabreTools.Compression
+{
+    /// <summary>
+    /// Derived from the mscorlib code from .NET Framework 4.0
+    /// </summary>
+    internal static class OldDotNet
+    {
+        public static void CopyTo(this Stream source, Stream destination)
+        {
+            if (destination == null)
+            {
+                throw new ArgumentNullException("destination");
+            }
+
+            if (!source.CanRead && !source.CanWrite)
+            {
+                throw new ObjectDisposedException(null);
+            }
+
+            if (!destination.CanRead && !destination.CanWrite)
+            {
+                throw new ObjectDisposedException("destination");
+            }
+
+            if (!source.CanRead)
+            {
+                throw new NotSupportedException();
+            }
+
+            if (!destination.CanWrite)
+            {
+                throw new NotSupportedException();
+            }
+
+            byte[] array = new byte[81920];
+            int count;
+            while ((count = source.Read(array, 0, array.Length)) != 0)
+            {
+                destination.Write(array, 0, count);
+            }
+        }
+    }
+}
+
+#endif
\ No newline at end of file
diff --git a/SabreTools.Compression.csproj b/SabreTools.Compression.csproj
index 2ea2ca2..5e94b3e 100644
--- a/SabreTools.Compression.csproj
+++ b/SabreTools.Compression.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <!-- Assembly Properties -->
-    <TargetFrameworks>net40;net452;net462;net472;net48;netcoreapp3.1;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net20;net35;net40;net452;net462;net472;net48;netcoreapp3.1;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
     <RuntimeIdentifiers>win-x86;win-x64;win-arm64;linux-x64;linux-arm64;osx-x64;osx-arm64</RuntimeIdentifiers>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <LangVersion>latest</LangVersion>