diff --git a/src/SharpCompress/Common/Lzw/LzwFilePart.cs b/src/SharpCompress/Common/Lzw/LzwFilePart.cs
index 707d16cd..087ab3aa 100644
--- a/src/SharpCompress/Common/Lzw/LzwFilePart.cs
+++ b/src/SharpCompress/Common/Lzw/LzwFilePart.cs
@@ -36,8 +36,15 @@ internal sealed partial class LzwFilePart : FilePart
 
     private static string? DeriveFileName(Stream stream)
     {
+        // Unwrap SharpCompressStream to get to the underlying FileStream
+        var unwrappedStream = stream;
+        if (stream is SharpCompress.IO.IStreamStack streamStack)
+        {
+            unwrappedStream = streamStack.BaseStream();
+        }
+
         // Try to derive filename from FileStream
-        if (stream is FileStream fileStream && !string.IsNullOrEmpty(fileStream.Name))
+        if (unwrappedStream is FileStream fileStream && !string.IsNullOrEmpty(fileStream.Name))
         {
             var fileName = Path.GetFileName(fileStream.Name);
             // Strip .Z extension if present
diff --git a/src/SharpCompress/packages.lock.json b/src/SharpCompress/packages.lock.json
index 29e7a1bd..27e9e496 100644
--- a/src/SharpCompress/packages.lock.json
+++ b/src/SharpCompress/packages.lock.json
@@ -216,9 +216,9 @@
     "net10.0": {
       "Microsoft.NET.ILLink.Tasks": {
         "type": "Direct",
-        "requested": "[10.0.0, )",
-        "resolved": "10.0.0",
-        "contentHash": "kICGrGYEzCNI3wPzfEXcwNHgTvlvVn9yJDhSdRK+oZQy4jvYH529u7O0xf5ocQKzOMjfS07+3z9PKRIjrFMJDA=="
+        "requested": "[10.0.2, )",
+        "resolved": "10.0.2",
+        "contentHash": "sXdDtMf2qcnbygw9OdE535c2lxSxrZP8gO4UhDJ0xiJbl1wIqXS1OTcTDFTIJPOFd6Mhcm8gPEthqWGUxBsTqw=="
       },
       "Microsoft.NETFramework.ReferenceAssemblies": {
         "type": "Direct",
@@ -264,9 +264,9 @@
     "net8.0": {
       "Microsoft.NET.ILLink.Tasks": {
         "type": "Direct",
-        "requested": "[8.0.22, )",
-        "resolved": "8.0.22",
-        "contentHash": "MhcMithKEiyyNkD2ZfbDZPmcOdi0GheGfg8saEIIEfD/fol3iHmcV8TsZkD4ZYz5gdUuoX4YtlVySUU7Sxl9SQ=="
+        "requested": "[8.0.23, )",
+        "resolved": "8.0.23",
+        "contentHash": "GqHiB1HbbODWPbY/lc5xLQH8siEEhNA0ptpJCC6X6adtAYNEzu5ZlqV3YHA3Gh7fuEwgA8XqVwMtH2KNtuQM1Q=="
       },
       "Microsoft.NETFramework.ReferenceAssemblies": {
         "type": "Direct",
diff --git a/tests/SharpCompress.Test/Lzw/LzwReaderAsyncTests.cs b/tests/SharpCompress.Test/Lzw/LzwReaderAsyncTests.cs
index b9083138..6ecc6047 100644
--- a/tests/SharpCompress.Test/Lzw/LzwReaderAsyncTests.cs
+++ b/tests/SharpCompress.Test/Lzw/LzwReaderAsyncTests.cs
@@ -1,4 +1,7 @@
+using System.IO;
 using SharpCompress.Common;
+using SharpCompress.Readers;
+using SharpCompress.Readers.Lzw;
 using Xunit;
 
 namespace SharpCompress.Test.Lzw;
@@ -12,4 +15,29 @@ public class LzwReaderAsyncTests : ReaderTests
     {
         await ReadAsync("Tar.tar.Z", CompressionType.Lzw);
     }
+
+    [Fact]
+    public async System.Threading.Tasks.Task Lzw_Reader_Plain_Z_File_Async()
+    {
+        // Test async reading of a plain .Z file (not tar-wrapped) using LzwReader directly
+        using Stream stream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, "large_test.txt.Z"));
+        using var reader = LzwReader.OpenReader(stream);
+
+        Assert.Equal(ArchiveType.Lzw, reader.ArchiveType);
+        Assert.True(reader.MoveToNextEntry());
+
+        var entry = reader.Entry;
+        Assert.NotNull(entry);
+        Assert.Equal(CompressionType.Lzw, entry.CompressionType);
+
+        // When opened as FileStream, key should be derived from filename
+        Assert.Equal("large_test.txt", entry.Key);
+
+        // Decompress asynchronously
+        using var entryStream = reader.OpenEntryStream();
+        using var ms = new MemoryStream();
+        await entryStream.CopyToAsync(ms);
+
+        Assert.Equal(22300, ms.Length);
+    }
 }
diff --git a/tests/SharpCompress.Test/Lzw/LzwReaderTests.cs b/tests/SharpCompress.Test/Lzw/LzwReaderTests.cs
index 4c7f2d6d..f75fd666 100644
--- a/tests/SharpCompress.Test/Lzw/LzwReaderTests.cs
+++ b/tests/SharpCompress.Test/Lzw/LzwReaderTests.cs
@@ -46,4 +46,46 @@ public class LzwReaderTests : ReaderTests
         Assert.NotNull(reader.Entry);
         Assert.Equal(CompressionType.Lzw, reader.Entry.CompressionType);
     }
+
+    [Fact]
+    public void Lzw_Reader_Plain_Z_File()
+    {
+        // Test with a plain .Z file (not tar-wrapped) using LzwReader directly
+        using Stream stream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, "large_test.txt.Z"));
+        using var reader = LzwReader.OpenReader(stream);
+
+        Assert.True(reader.MoveToNextEntry());
+        var entry = reader.Entry;
+        Assert.NotNull(entry);
+        Assert.Equal(CompressionType.Lzw, entry.CompressionType);
+
+        // Entry key should be "large_test.txt" (stripped .Z extension) when opened via FileStream
+        Assert.Equal("large_test.txt", entry.Key);
+
+        // Decompress and verify content
+        using var entryStream = reader.OpenEntryStream();
+        using var ms = new MemoryStream();
+        entryStream.CopyTo(ms);
+        var decompressed = System.Text.Encoding.UTF8.GetString(ms.ToArray());
+
+        Assert.Equal(22300, ms.Length);
+        Assert.Contains("This is a test file for LZW compression testing", decompressed);
+    }
+
+    [Fact]
+    public void Lzw_Reader_Factory_Detects_Plain_Z_File()
+    {
+        // Test that ReaderFactory correctly identifies a plain .Z file (not tar-wrapped)
+        using Stream stream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, "large_test.txt.Z"));
+        using var reader = ReaderFactory.OpenReader(stream);
+
+        // Should detect as Lzw archive (not Tar)
+        Assert.Equal(ArchiveType.Lzw, reader.ArchiveType);
+        Assert.True(reader.MoveToNextEntry());
+        Assert.NotNull(reader.Entry);
+        Assert.Equal(CompressionType.Lzw, reader.Entry.CompressionType);
+
+        // When opened via ReaderFactory with a non-FileStream, key defaults to "data"
+        Assert.NotNull(reader.Entry.Key);
+    }
 }
diff --git a/tests/TestArchives/Archives/large_test.txt.Z b/tests/TestArchives/Archives/large_test.txt.Z
new file mode 100644
index 00000000..64ae2af1
Binary files /dev/null and b/tests/TestArchives/Archives/large_test.txt.Z differ