diff --git a/src/SharpCompress/Archives/AbstractWritableArchive.cs b/src/SharpCompress/Archives/AbstractWritableArchive.cs
index 84ca0b3f..ef272d9b 100644
--- a/src/SharpCompress/Archives/AbstractWritableArchive.cs
+++ b/src/SharpCompress/Archives/AbstractWritableArchive.cs
@@ -120,6 +120,10 @@ public abstract class AbstractWritableArchive<TEntry, TVolume>
     {
         foreach (var path in Entries.Select(x => x.Key))
         {
+            if (path is null)
+            {
+                continue;
+            }
             var p = path.Replace('/', '\\');
             if (p.Length > 0 && p[0] == '\\')
             {
diff --git a/src/SharpCompress/Archives/GZip/GZipArchive.cs b/src/SharpCompress/Archives/GZip/GZipArchive.cs
index 70924b04..88247222 100644
--- a/src/SharpCompress/Archives/GZip/GZipArchive.cs
+++ b/src/SharpCompress/Archives/GZip/GZipArchive.cs
@@ -184,7 +184,7 @@ public class GZipArchive : AbstractWritableArchive<GZipArchiveEntry, GZipVolume>
         foreach (var entry in oldEntries.Concat(newEntries).Where(x => !x.IsDirectory))
         {
             using var entryStream = entry.OpenEntryStream();
-            writer.Write(entry.Key, entryStream, entry.LastModifiedTime);
+            writer.Write(entry.Key.NotNull("Entry Key is null"), entryStream, entry.LastModifiedTime);
         }
     }
 
diff --git a/src/SharpCompress/Archives/IArchiveEntryExtensions.cs b/src/SharpCompress/Archives/IArchiveEntryExtensions.cs
index 0992f152..3d1daa1a 100644
--- a/src/SharpCompress/Archives/IArchiveEntryExtensions.cs
+++ b/src/SharpCompress/Archives/IArchiveEntryExtensions.cs
@@ -17,15 +17,11 @@ public static class IArchiveEntryExtensions
         streamListener.EnsureEntriesLoaded();
         streamListener.FireEntryExtractionBegin(archiveEntry);
         streamListener.FireFilePartExtractionBegin(
-            archiveEntry.Key,
+            archiveEntry.Key ?? "Key",
             archiveEntry.Size,
             archiveEntry.CompressedSize
         );
         var entryStream = archiveEntry.OpenEntryStream();
-        if (entryStream is null)
-        {
-            return;
-        }
         using (entryStream)
         {
             using Stream s = new ListeningStream(streamListener, entryStream);
diff --git a/src/SharpCompress/Archives/IArchiveExtensions.cs b/src/SharpCompress/Archives/IArchiveExtensions.cs
index 56ea0d9f..382c3ddf 100644
--- a/src/SharpCompress/Archives/IArchiveExtensions.cs
+++ b/src/SharpCompress/Archives/IArchiveExtensions.cs
@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Threading;
-using System.Threading.Tasks;
 using SharpCompress.Common;
 
 namespace SharpCompress.Archives;
@@ -59,7 +58,7 @@ public static class IArchiveExtensions
             }
 
             // Create each directory
-            var path = Path.Combine(destination, entry.Key);
+            var path = Path.Combine(destination, entry.Key.NotNull("Entry Key is null"));
             if (Path.GetDirectoryName(path) is { } directory && seenDirectories.Add(path))
             {
                 Directory.CreateDirectory(directory);
diff --git a/src/SharpCompress/Common/Entry.cs b/src/SharpCompress/Common/Entry.cs
index 85219a43..6209b3de 100644
--- a/src/SharpCompress/Common/Entry.cs
+++ b/src/SharpCompress/Common/Entry.cs
@@ -14,7 +14,7 @@ public abstract class Entry : IEntry
     /// <summary>
     /// The string key of the file internal to the Archive.
     /// </summary>
-    public abstract string Key { get; }
+    public abstract string? Key { get; }
 
     /// <summary>
     /// The target of a symlink entry internal to the Archive. Will be null if not a symlink.
@@ -71,11 +71,11 @@ public abstract class Entry : IEntry
     /// </summary>
     public abstract bool IsSplitAfter { get; }
 
-    public int VolumeIndexFirst => Parts?.FirstOrDefault()?.Index ?? 0;
-    public int VolumeIndexLast => Parts?.LastOrDefault()?.Index ?? 0;
+    public int VolumeIndexFirst => Parts.FirstOrDefault()?.Index ?? 0;
+    public int VolumeIndexLast => Parts.LastOrDefault()?.Index ?? 0;
 
     /// <inheritdoc/>
-    public override string ToString() => Key;
+    public override string ToString() => Key ?? "Entry";
 
     internal abstract IEnumerable<FilePart> Parts { get; }
 
diff --git a/src/SharpCompress/Common/ExtractionMethods.cs b/src/SharpCompress/Common/ExtractionMethods.cs
index a470637a..4a24ad9e 100644
--- a/src/SharpCompress/Common/ExtractionMethods.cs
+++ b/src/SharpCompress/Common/ExtractionMethods.cs
@@ -36,10 +36,10 @@ internal static class ExtractionMethods
 
         options ??= new ExtractionOptions() { Overwrite = true };
 
-        var file = Path.GetFileName(entry.Key);
+        var file = Path.GetFileName(entry.Key.NotNull("Entry Key is null")).NotNull("File is null");
         if (options.ExtractFullPath)
         {
-            var folder = Path.GetDirectoryName(entry.Key)!;
+            var folder = Path.GetDirectoryName(entry.Key.NotNull("Entry Key is null")).NotNull("Directory is null");
             var destdir = Path.GetFullPath(Path.Combine(fullDestinationDirectoryPath, folder));
 
             if (!Directory.Exists(destdir))
diff --git a/src/SharpCompress/Common/FilePart.cs b/src/SharpCompress/Common/FilePart.cs
index 3c286d54..23b8b400 100644
--- a/src/SharpCompress/Common/FilePart.cs
+++ b/src/SharpCompress/Common/FilePart.cs
@@ -8,7 +8,7 @@ public abstract class FilePart
 
     internal ArchiveEncoding ArchiveEncoding { get; }
 
-    internal abstract string FilePartName { get; }
+    internal abstract string? FilePartName { get; }
     public int Index { get; set; }
 
     internal abstract Stream GetCompressedStream();
diff --git a/src/SharpCompress/Common/GZip/GZipEntry.cs b/src/SharpCompress/Common/GZip/GZipEntry.cs
index bb9a22da..bd341d24 100644
--- a/src/SharpCompress/Common/GZip/GZipEntry.cs
+++ b/src/SharpCompress/Common/GZip/GZipEntry.cs
@@ -14,7 +14,7 @@ public class GZipEntry : Entry
 
     public override long Crc => _filePart.Crc ?? 0;
 
-    public override string Key => _filePart.FilePartName;
+    public override string? Key => _filePart.FilePartName;
 
     public override string? LinkTarget => null;
 
diff --git a/src/SharpCompress/Common/GZip/GZipFilePart.cs b/src/SharpCompress/Common/GZip/GZipFilePart.cs
index fbf4ee45..4a1c9515 100644
--- a/src/SharpCompress/Common/GZip/GZipFilePart.cs
+++ b/src/SharpCompress/Common/GZip/GZipFilePart.cs
@@ -34,7 +34,7 @@ internal sealed class GZipFilePart : FilePart
     internal uint? Crc { get; private set; }
     internal uint? UncompressedSize { get; private set; }
 
-    internal override string FilePartName => _name!;
+    internal override string? FilePartName => _name;
 
     internal override Stream GetCompressedStream() =>
         new DeflateStream(_stream, CompressionMode.Decompress, CompressionLevel.Default);
diff --git a/src/SharpCompress/Common/IEntry.cs b/src/SharpCompress/Common/IEntry.cs
index df1fa603..56e1db81 100644
--- a/src/SharpCompress/Common/IEntry.cs
+++ b/src/SharpCompress/Common/IEntry.cs
@@ -9,7 +9,7 @@ public interface IEntry
     long CompressedSize { get; }
     long Crc { get; }
     DateTime? CreatedTime { get; }
-    string Key { get; }
+    string? Key { get; }
     string? LinkTarget { get; }
     bool IsDirectory { get; }
     bool IsEncrypted { get; }
diff --git a/src/SharpCompress/Common/IVolume.cs b/src/SharpCompress/Common/IVolume.cs
index abbc0406..aed35fd0 100644
--- a/src/SharpCompress/Common/IVolume.cs
+++ b/src/SharpCompress/Common/IVolume.cs
@@ -6,5 +6,5 @@ public interface IVolume : IDisposable
 {
     int Index { get; }
 
-    string FileName { get; }
+    string? FileName { get; }
 }
diff --git a/src/SharpCompress/Common/Rar/RarCryptoWrapper.cs b/src/SharpCompress/Common/Rar/RarCryptoWrapper.cs
index a9798609..5500af8d 100644
--- a/src/SharpCompress/Common/Rar/RarCryptoWrapper.cs
+++ b/src/SharpCompress/Common/Rar/RarCryptoWrapper.cs
@@ -70,11 +70,11 @@ internal sealed class RarCryptoWrapper : Stream
 
     protected override void Dispose(bool disposing)
     {
-        if (_rijndael != null)
+        if (disposing)
         {
             _rijndael.Dispose();
-            _rijndael = null!;
         }
+
         base.Dispose(disposing);
     }
 }
diff --git a/src/SharpCompress/Common/SevenZip/ArchiveDatabase.cs b/src/SharpCompress/Common/SevenZip/ArchiveDatabase.cs
index ee6f6d08..4bac08ad 100644
--- a/src/SharpCompress/Common/SevenZip/ArchiveDatabase.cs
+++ b/src/SharpCompress/Common/SevenZip/ArchiveDatabase.cs
@@ -35,7 +35,7 @@ internal class ArchiveDatabase
         _packSizes.Clear();
         _packCrCs.Clear();
         _folders.Clear();
-        _numUnpackStreamsVector = null!;
+        _numUnpackStreamsVector = null;
         _files.Clear();
 
         _packStreamStartPositions.Clear();
diff --git a/src/SharpCompress/Common/Volume.cs b/src/SharpCompress/Common/Volume.cs
index 1f259257..a29dab75 100644
--- a/src/SharpCompress/Common/Volume.cs
+++ b/src/SharpCompress/Common/Volume.cs
@@ -32,7 +32,7 @@ public abstract class Volume : IVolume
 
     public virtual int Index { get; internal set; }
 
-    public string FileName => (_actualStream as FileStream)?.Name!;
+    public string? FileName => (_actualStream as FileStream)?.Name;
 
     /// <summary>
     /// RarArchive is part of a multi-part archive.
diff --git a/src/SharpCompress/IO/SourceStream.cs b/src/SharpCompress/IO/SourceStream.cs
index 26ce0af1..46c0a3f6 100644
--- a/src/SharpCompress/IO/SourceStream.cs
+++ b/src/SharpCompress/IO/SourceStream.cs
@@ -11,8 +11,8 @@ public class SourceStream : Stream
     private long _prevSize;
     private readonly List<FileInfo> _files;
     private readonly List<Stream> _streams;
-    private readonly Func<int, FileInfo?> _getFilePart;
-    private readonly Func<int, Stream?> _getStreamPart;
+    private readonly Func<int, FileInfo?>? _getFilePart;
+    private readonly Func<int, Stream?>? _getStreamPart;
     private int _stream;
 
     public SourceStream(FileInfo file, Func<int, FileInfo?> getPart, ReaderOptions options)
@@ -38,8 +38,8 @@ public class SourceStream : Stream
         if (!IsFileMode)
         {
             _streams.Add(stream!);
-            _getStreamPart = getStreamPart!;
-            _getFilePart = _ => null!;
+            _getStreamPart = getStreamPart;
+            _getFilePart = _ => null;
             if (stream is FileStream fileStream)
             {
                 _files.Add(new FileInfo(fileStream.Name));
@@ -49,8 +49,8 @@ public class SourceStream : Stream
         {
             _files.Add(file!);
             _streams.Add(_files[0].OpenRead());
-            _getFilePart = getFilePart!;
-            _getStreamPart = _ => null!;
+            _getFilePart = getFilePart;
+            _getStreamPart = _ => null;
         }
         _stream = 0;
         _prevSize = 0;
@@ -78,7 +78,7 @@ public class SourceStream : Stream
         {
             if (IsFileMode)
             {
-                var f = _getFilePart(_streams.Count);
+                var f = _getFilePart.NotNull("GetFilePart is null")(_streams.Count);
                 if (f == null)
                 {
                     _stream = _streams.Count - 1;
@@ -90,7 +90,7 @@ public class SourceStream : Stream
             }
             else
             {
-                var s = _getStreamPart(_streams.Count);
+                var s = _getStreamPart.NotNull("GetStreamPart is null")(_streams.Count);
                 if (s == null)
                 {
                     _stream = _streams.Count - 1;
diff --git a/src/SharpCompress/Readers/AbstractReader.cs b/src/SharpCompress/Readers/AbstractReader.cs
index 53069414..a0d982f1 100644
--- a/src/SharpCompress/Readers/AbstractReader.cs
+++ b/src/SharpCompress/Readers/AbstractReader.cs
@@ -35,7 +35,7 @@ public abstract class AbstractReader<TEntry, TVolume> : IReader, IReaderExtracti
     /// <summary>
     /// Current volume that the current entry resides in
     /// </summary>
-    public abstract TVolume Volume { get; }
+    public abstract TVolume? Volume { get; }
 
     /// <summary>
     /// Current file entry
@@ -109,7 +109,7 @@ public abstract class AbstractReader<TEntry, TVolume> : IReader, IReaderExtracti
         return entriesForCurrentReadStream.MoveNext();
     }
 
-    protected virtual Stream RequestInitialStream() => Volume.Stream;
+    protected virtual Stream RequestInitialStream() => Volume.NotNull("Volume isn't loaded.").Stream;
 
     internal virtual bool NextEntryForCurrentStream() => entriesForCurrentReadStream!.MoveNext();
 
diff --git a/src/SharpCompress/Readers/Rar/RarReader.cs b/src/SharpCompress/Readers/Rar/RarReader.cs
index a46d2852..f092699d 100644
--- a/src/SharpCompress/Readers/Rar/RarReader.cs
+++ b/src/SharpCompress/Readers/Rar/RarReader.cs
@@ -19,11 +19,13 @@ public abstract class RarReader : AbstractReader<RarReaderEntry, RarVolume>
     internal Lazy<IRarUnpack> UnpackV1 { get; } = new(() => new Compressors.Rar.UnpackV1.Unpack());
 
     internal RarReader(ReaderOptions options)
-        : base(options, ArchiveType.Rar) { }
+        : base(options, ArchiveType.Rar)
+    {
+    }
 
     internal abstract void ValidateArchive(RarVolume archive);
 
-    public override RarVolume Volume => volume!;
+    public override RarVolume? Volume => volume;
 
     /// <summary>
     /// Opens a RarReader for Non-seeking usage with a single volume
diff --git a/src/SharpCompress/Utility.cs b/src/SharpCompress/Utility.cs
index bcecafb4..74f6037a 100644
--- a/src/SharpCompress/Utility.cs
+++ b/src/SharpCompress/Utility.cs
@@ -9,6 +9,22 @@ namespace SharpCompress;
 [CLSCompliant(false)]
 public static class Utility
 {
+    public static T NotNull<T>(this T? item, string message) where T : class
+    {
+        if (item is null)
+        {
+            throw new InvalidOperationException(message);
+        }
+        return item;
+    }
+    public static T NotNull<T>(this T? item) where T : class
+    {
+        if (item is null)
+        {
+            throw new InvalidOperationException("Item is null");
+        }
+        return item;
+    }
     public static ReadOnlyCollection<T> ToReadOnly<T>(this ICollection<T> items) => new(items);
 
     /// <summary>
diff --git a/tests/SharpCompress.Test/GZip/GZipArchiveTests.cs b/tests/SharpCompress.Test/GZip/GZipArchiveTests.cs
index 5b497d9f..80a9a9a1 100644
--- a/tests/SharpCompress.Test/GZip/GZipArchiveTests.cs
+++ b/tests/SharpCompress.Test/GZip/GZipArchiveTests.cs
@@ -19,7 +19,7 @@ public class GZipArchiveTests : ArchiveTests
         using (var archive = ArchiveFactory.Open(stream))
         {
             var entry = archive.Entries.First();
-            entry.WriteToFile(Path.Combine(SCRATCH_FILES_PATH, entry.Key));
+            entry.WriteToFile(Path.Combine(SCRATCH_FILES_PATH, entry.Key.NotNull()));
 
             var size = entry.Size;
             var scratch = new FileInfo(Path.Combine(SCRATCH_FILES_PATH, "Tar.tar"));
@@ -41,7 +41,7 @@ public class GZipArchiveTests : ArchiveTests
         using (var archive = GZipArchive.Open(stream))
         {
             var entry = archive.Entries.First();
-            entry.WriteToFile(Path.Combine(SCRATCH_FILES_PATH, entry.Key));
+            entry.WriteToFile(Path.Combine(SCRATCH_FILES_PATH, entry.Key.NotNull()));
 
             var size = entry.Size;
             var scratch = new FileInfo(Path.Combine(SCRATCH_FILES_PATH, "Tar.tar"));
@@ -94,6 +94,7 @@ public class GZipArchiveTests : ArchiveTests
         using (var entryStream = archiveEntry.OpenEntryStream())
         {
             var result = TarArchive.IsTarFile(entryStream);
+            Assert.True(result);
         }
         Assert.Equal(size, tarStream.Length);
         using (var entryStream = archiveEntry.OpenEntryStream())
diff --git a/tests/SharpCompress.Test/Rar/RarReaderTests.cs b/tests/SharpCompress.Test/Rar/RarReaderTests.cs
index e2b100f6..6ba605a5 100644
--- a/tests/SharpCompress.Test/Rar/RarReaderTests.cs
+++ b/tests/SharpCompress.Test/Rar/RarReaderTests.cs
@@ -209,7 +209,7 @@ public class RarReaderTests : ReaderTests
                 {
                     Assert.Equal(CompressionType.Rar, reader.Entry.CompressionType);
                     using var entryStream = reader.OpenEntryStream();
-                    var file = Path.GetFileName(reader.Entry.Key);
+                    var file = Path.GetFileName(reader.Entry.Key).NotNull();
                     var folder =
                         Path.GetDirectoryName(reader.Entry.Key)
                         ?? throw new ArgumentNullException();
@@ -293,7 +293,7 @@ public class RarReaderTests : ReaderTests
         using var reader = ReaderFactory.Open(stream, new ReaderOptions { LookForHeader = true });
         while (reader.MoveToNextEntry())
         {
-            if (reader.Entry.Key.Contains("jpg"))
+            if (reader.Entry.Key.NotNull().Contains("jpg"))
             {
                 Assert.Equal(CompressionType.Rar, reader.Entry.CompressionType);
                 reader.WriteEntryToDirectory(
@@ -316,7 +316,7 @@ public class RarReaderTests : ReaderTests
         using var reader = ReaderFactory.Open(stream, new ReaderOptions { LookForHeader = true });
         while (reader.MoveToNextEntry())
         {
-            if (reader.Entry.Key.Contains("jpg"))
+            if (reader.Entry.Key.NotNull().Contains("jpg"))
             {
                 Assert.Equal(CompressionType.Rar, reader.Entry.CompressionType);
                 reader.WriteEntryToDirectory(
diff --git a/tests/SharpCompress.Test/TestBase.cs b/tests/SharpCompress.Test/TestBase.cs
index ad39b2d7..184e6442 100644
--- a/tests/SharpCompress.Test/TestBase.cs
+++ b/tests/SharpCompress.Test/TestBase.cs
@@ -216,8 +216,8 @@ public class TestBase : IDisposable
             while (archive1.MoveToNextEntry())
             {
                 Assert.True(archive2.MoveToNextEntry());
-                archive1Entries.Add(archive1.Entry.Key);
-                archive2Entries.Add(archive2.Entry.Key);
+                archive1Entries.Add(archive1.Entry.Key.NotNull());
+                archive2Entries.Add(archive2.Entry.Key.NotNull());
             }
             Assert.False(archive2.MoveToNextEntry());
         }
diff --git a/tests/SharpCompress.Test/Zip/ZipArchiveTests.cs b/tests/SharpCompress.Test/Zip/ZipArchiveTests.cs
index 1948b26a..afbe7c9e 100644
--- a/tests/SharpCompress.Test/Zip/ZipArchiveTests.cs
+++ b/tests/SharpCompress.Test/Zip/ZipArchiveTests.cs
@@ -258,7 +258,7 @@ public class ZipArchiveTests : ArchiveTests
         );
         Assert.Null(
             ((IArchive)vfs).Entries.FirstOrDefault(v =>
-                v.Key.EndsWith("jpg", StringComparison.OrdinalIgnoreCase)
+                v.Key.NotNull().EndsWith("jpg", StringComparison.OrdinalIgnoreCase)
             )
         );
     }