diff --git a/src/ImageSharp/Compression/Zlib/DeflateThrowHelper.cs b/src/ImageSharp/Compression/Zlib/DeflateThrowHelper.cs
index ba22d5d85..30761328f 100644
--- a/src/ImageSharp/Compression/Zlib/DeflateThrowHelper.cs
+++ b/src/ImageSharp/Compression/Zlib/DeflateThrowHelper.cs
@@ -1,23 +1,33 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using System.Diagnostics.CodeAnalysis;
+
 namespace SixLabors.ImageSharp.Compression.Zlib;
 
 internal static class DeflateThrowHelper
 {
+    [DoesNotReturn]
     public static void ThrowAlreadyFinished() => throw new InvalidOperationException("Finish() already called.");
 
+    [DoesNotReturn]
     public static void ThrowAlreadyClosed() => throw new InvalidOperationException("Deflator already closed.");
 
+    [DoesNotReturn]
     public static void ThrowUnknownCompression() => throw new InvalidOperationException("Unknown compression function.");
 
+    [DoesNotReturn]
     public static void ThrowNotProcessed() => throw new InvalidOperationException("Old input was not completely processed.");
 
+    [DoesNotReturn]
     public static void ThrowNull(string name) => throw new ArgumentNullException(name);
 
+    [DoesNotReturn]
     public static void ThrowOutOfRange(string name) => throw new ArgumentOutOfRangeException(name);
 
+    [DoesNotReturn]
     public static void ThrowHeapViolated() => throw new InvalidOperationException("Huffman heap invariant violated.");
 
+    [DoesNotReturn]
     public static void ThrowNoDeflate() => throw new ImageFormatException("Cannot deflate all input.");
 }
diff --git a/src/ImageSharp/Compression/Zlib/Deflater.cs b/src/ImageSharp/Compression/Zlib/Deflater.cs
index f001b8a67..f642ec85a 100644
--- a/src/ImageSharp/Compression/Zlib/Deflater.cs
+++ b/src/ImageSharp/Compression/Zlib/Deflater.cs
@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Memory;
@@ -285,7 +284,6 @@ internal sealed class Deflater : IDisposable
         if (!this.isDisposed)
         {
             this.engine.Dispose();
-            this.engine = null;
             this.isDisposed = true;
         }
     }
diff --git a/src/ImageSharp/Compression/Zlib/DeflaterEngine.cs b/src/ImageSharp/Compression/Zlib/DeflaterEngine.cs
index 47bc43f52..31fa0238b 100644
--- a/src/ImageSharp/Compression/Zlib/DeflaterEngine.cs
+++ b/src/ImageSharp/Compression/Zlib/DeflaterEngine.cs
@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers;
 using System.Runtime.CompilerServices;
@@ -87,7 +86,7 @@ internal sealed unsafe class DeflaterEngine : IDisposable
     /// <summary>
     /// The input data for compression.
     /// </summary>
-    private byte[] inputBuf;
+    private byte[]? inputBuf;
 
     /// <summary>
     /// The offset into inputBuf, where input data starts.
@@ -222,7 +221,7 @@ internal sealed unsafe class DeflaterEngine : IDisposable
     /// <param name="buffer">The buffer containing input data.</param>
     /// <param name="offset">The offset of the first byte of data.</param>
     /// <param name="count">The number of bytes of data to use as input.</param>
-    public void SetInput(byte[] buffer, int offset, int count)
+    public void SetInput(byte[]? buffer, int offset, int count)
     {
         if (buffer is null)
         {
@@ -362,6 +361,8 @@ internal sealed unsafe class DeflaterEngine : IDisposable
                 more = this.inputEnd - this.inputOff;
             }
 
+            ArgumentNullException.ThrowIfNull(this.inputBuf);
+
             Unsafe.CopyBlockUnaligned(
                 ref this.window.Span[this.strstart + this.lookahead],
                 ref this.inputBuf[this.inputOff],
@@ -393,11 +394,6 @@ internal sealed unsafe class DeflaterEngine : IDisposable
             this.prevMemoryHandle.Dispose();
             this.prevMemoryOwner.Dispose();
 
-            this.windowMemoryOwner = null;
-            this.headMemoryOwner = null;
-            this.prevMemoryOwner = null;
-            this.huffman = null;
-
             this.isDisposed = true;
         }
     }
diff --git a/src/ImageSharp/Compression/Zlib/DeflaterHuffman.cs b/src/ImageSharp/Compression/Zlib/DeflaterHuffman.cs
index 8c6769908..dc11de425 100644
--- a/src/ImageSharp/Compression/Zlib/DeflaterHuffman.cs
+++ b/src/ImageSharp/Compression/Zlib/DeflaterHuffman.cs
@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers;
 using System.Runtime.CompilerServices;
@@ -427,10 +426,6 @@ internal sealed unsafe class DeflaterHuffman : IDisposable
             this.blTree.Dispose();
             this.distTree.Dispose();
 
-            this.Pending = null;
-            this.literalTree = null;
-            this.blTree = null;
-            this.distTree = null;
             this.isDisposed = true;
         }
     }
@@ -977,10 +972,6 @@ internal sealed unsafe class DeflaterHuffman : IDisposable
                 this.codesMemoryHandle.Dispose();
                 this.codesMemoryOwner.Dispose();
 
-                this.frequenciesMemoryOwner = null;
-                this.lengthsMemoryOwner = null;
-                this.codesMemoryOwner = null;
-
                 this.isDisposed = true;
             }
         }
diff --git a/src/ImageSharp/Compression/Zlib/DeflaterOutputStream.cs b/src/ImageSharp/Compression/Zlib/DeflaterOutputStream.cs
index cea2fd272..de818fd8f 100644
--- a/src/ImageSharp/Compression/Zlib/DeflaterOutputStream.cs
+++ b/src/ImageSharp/Compression/Zlib/DeflaterOutputStream.cs
@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers;
 using SixLabors.ImageSharp.Memory;
@@ -137,8 +136,6 @@ internal sealed class DeflaterOutputStream : Stream
                 this.memoryOwner.Dispose();
             }
 
-            this.deflater = null;
-            this.memoryOwner = null;
             this.isDisposed = true;
             base.Dispose(disposing);
         }
diff --git a/src/ImageSharp/Compression/Zlib/DeflaterPendingBuffer.cs b/src/ImageSharp/Compression/Zlib/DeflaterPendingBuffer.cs
index 28febdc11..37e7404e4 100644
--- a/src/ImageSharp/Compression/Zlib/DeflaterPendingBuffer.cs
+++ b/src/ImageSharp/Compression/Zlib/DeflaterPendingBuffer.cs
@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Buffers;
 using System.Runtime.CompilerServices;
@@ -180,7 +179,6 @@ internal sealed unsafe class DeflaterPendingBuffer : IDisposable
         {
             this.bufferMemoryHandle.Dispose();
             this.bufferMemoryOwner.Dispose();
-            this.bufferMemoryOwner = null;
             this.isDisposed = true;
         }
     }
diff --git a/src/ImageSharp/Compression/Zlib/ZlibDeflateStream.cs b/src/ImageSharp/Compression/Zlib/ZlibDeflateStream.cs
index 00c4aed3b..2e52f84d7 100644
--- a/src/ImageSharp/Compression/Zlib/ZlibDeflateStream.cs
+++ b/src/ImageSharp/Compression/Zlib/ZlibDeflateStream.cs
@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Formats.Png;
@@ -172,8 +171,6 @@ internal sealed class ZlibDeflateStream : Stream
             this.rawStream.WriteByte((byte)(crc & 0xFF));
         }
 
-        this.deflateStream = null;
-
         base.Dispose(disposing);
         this.isDisposed = true;
     }
diff --git a/src/ImageSharp/Compression/Zlib/ZlibInflateStream.cs b/src/ImageSharp/Compression/Zlib/ZlibInflateStream.cs
index f9e678605..06a7c3928 100644
--- a/src/ImageSharp/Compression/Zlib/ZlibInflateStream.cs
+++ b/src/ImageSharp/Compression/Zlib/ZlibInflateStream.cs
@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
+using System.Diagnostics.CodeAnalysis;
 using System.IO.Compression;
 using SixLabors.ImageSharp.IO;
 
@@ -90,7 +90,7 @@ internal sealed class ZlibInflateStream : Stream
     /// <summary>
     /// Gets the compressed stream over the deframed inner stream.
     /// </summary>
-    public DeflateStream CompressedStream { get; private set; }
+    public DeflateStream? CompressedStream { get; private set; }
 
     /// <summary>
     /// Adds new bytes from a frame found in the original stream.
@@ -98,6 +98,7 @@ internal sealed class ZlibInflateStream : Stream
     /// <param name="bytes">The current remaining data according to the chunk length.</param>
     /// <param name="isCriticalChunk">Whether the chunk to be inflated is a critical chunk.</param>
     /// <returns>The <see cref="bool"/>.</returns>
+    [MemberNotNullWhen(true, nameof(CompressedStream))]
     public bool AllocateNewBytes(int bytes, bool isCriticalChunk)
     {
         this.currentDataRemaining = bytes;
@@ -210,6 +211,7 @@ internal sealed class ZlibInflateStream : Stream
         this.isDisposed = true;
     }
 
+    [MemberNotNullWhen(true, nameof(CompressedStream))]
     private bool InitializeInflateStream(bool isCriticalChunk)
     {
         // Read the zlib header : http://tools.ietf.org/html/rfc1950
diff --git a/src/ImageSharp/Diagnostics/MemoryDiagnostics.cs b/src/ImageSharp/Diagnostics/MemoryDiagnostics.cs
index f00ee1b2a..8327daf23 100644
--- a/src/ImageSharp/Diagnostics/MemoryDiagnostics.cs
+++ b/src/ImageSharp/Diagnostics/MemoryDiagnostics.cs
@@ -1,6 +1,5 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
-#nullable disable
 
 namespace SixLabors.ImageSharp.Diagnostics;
 
@@ -17,7 +16,7 @@ public static class MemoryDiagnostics
 {
     private static int totalUndisposedAllocationCount;
 
-    private static UndisposedAllocationDelegate undisposedAllocation;
+    private static UndisposedAllocationDelegate? undisposedAllocation;
     private static int undisposedAllocationSubscriptionCounter;
     private static readonly object SyncRoot = new();
 
@@ -50,12 +49,12 @@ public static class MemoryDiagnostics
     /// <summary>
     /// Fires when ImageSharp allocates memory from a MemoryAllocator
     /// </summary>
-    internal static event Action MemoryAllocated;
+    internal static event Action? MemoryAllocated;
 
     /// <summary>
     /// Fires when ImageSharp releases memory allocated from a MemoryAllocator
     /// </summary>
-    internal static event Action MemoryReleased;
+    internal static event Action? MemoryReleased;
 
     /// <summary>
     /// Gets a value indicating the total number of memory resource objects leaked to the finalizer.
diff --git a/src/ImageSharp/Formats/Tiff/Compression/Decompressors/DeflateTiffCompression.cs b/src/ImageSharp/Formats/Tiff/Compression/Decompressors/DeflateTiffCompression.cs
index 4c377c878..27c311009 100644
--- a/src/ImageSharp/Formats/Tiff/Compression/Decompressors/DeflateTiffCompression.cs
+++ b/src/ImageSharp/Formats/Tiff/Compression/Decompressors/DeflateTiffCompression.cs
@@ -50,19 +50,21 @@ internal sealed class DeflateTiffCompression : TiffBaseDecompressor
                 return left > 0 ? left : 0;
             }))
         {
-            deframeStream.AllocateNewBytes(byteCount, true);
-            DeflateStream dataStream = deframeStream.CompressedStream;
-
-            int totalRead = 0;
-            while (totalRead < buffer.Length)
+            if (deframeStream.AllocateNewBytes(byteCount, true))
             {
-                int bytesRead = dataStream.Read(buffer, totalRead, buffer.Length - totalRead);
-                if (bytesRead <= 0)
+                DeflateStream? dataStream = deframeStream.CompressedStream;
+
+                int totalRead = 0;
+                while (totalRead < buffer.Length)
                 {
-                    break;
-                }
+                    int bytesRead = dataStream.Read(buffer, totalRead, buffer.Length - totalRead);
+                    if (bytesRead <= 0)
+                    {
+                        break;
+                    }
 
-                totalRead += bytesRead;
+                    totalRead += bytesRead;
+                }
             }
         }