diff --git a/Net/DistributedRoutingTable.cs b/Net/DistributedRoutingTable.cs
index 5cfd98af..96dd0633 100644
--- a/Net/DistributedRoutingTable.cs
+++ b/Net/DistributedRoutingTable.cs
@@ -312,13 +312,13 @@ public class DistributedRoutingTable : IDisposable
 			switch (pEventData.Value.type)
 			{
 				case DRT_EVENT_TYPE.DRT_EVENT_STATUS_CHANGED:
-					Drt.StatusChange?.Invoke(Drt, new(pEventData.Value));
+					Drt?.StatusChange?.Invoke(Drt, new(pEventData.Value));
 					break;
 				case DRT_EVENT_TYPE.DRT_EVENT_LEAFSET_KEY_CHANGED:
-					Drt.LeafSetKeyChange?.Invoke(Drt, new(pEventData.Value));
+					Drt?.LeafSetKeyChange?.Invoke(Drt, new(pEventData.Value));
 					break;
 				case DRT_EVENT_TYPE.DRT_EVENT_REGISTRATION_STATE_CHANGED:
-					Drt.RegistrationStateChange?.Invoke(Drt, new(pEventData.Value));
+					Drt?.RegistrationStateChange?.Invoke(Drt, new(pEventData.Value));
 					break;
 			}
 		}
diff --git a/PInvoke/CoreAudio/AudioClient.cs b/PInvoke/CoreAudio/AudioClient.cs
index 5d0d2a6a..1e5a51aa 100644
--- a/PInvoke/CoreAudio/AudioClient.cs
+++ b/PInvoke/CoreAudio/AudioClient.cs
@@ -11,9 +11,13 @@ public static partial class CoreAudio
 	/// <summary>Undocumented</summary>
 	public const uint AMBISONICS_PARAM_VERSION_1 = 1;
 
+	/// <summary/>
 	public const uint WM_APP_GRAPHNOTIFY = 0x8002;
+	/// <summary/>
 	public const uint WM_APP_SESSION_DUCKED = 0x8000;
+	/// <summary/>
 	public const uint WM_APP_SESSION_UNDUCKED = 0x8001;
+	/// <summary/>
 	public const uint WM_APP_SESSION_VOLUME_CHANGED = 0x8003;
 
 	/// <summary>Undocumented</summary>
@@ -151,20 +155,25 @@ public static partial class CoreAudio
 		HRESULT SetEchoCancellationRenderEndpoint([MarshalAs(UnmanagedType.LPWStr)] string endpointId);
 	}
 
+	/// <summary>Undocumented</summary>
 	[PInvokeData("audioclient.h")]
 	[ComImport, Guid("28724C91-DF35-4856-9F76-D6A26413F3DF"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
 	public interface IAudioAmbisonicsControl
 	{
+		/// <summary>Undocumented</summary>
 		[PreserveSig]
 		HRESULT SetData([In, MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)] AMBISONICS_PARAMS[] pAmbisonicsParams,
 			uint cbAmbisonicsParams);
 
+		/// <summary>Undocumented</summary>
 		[PreserveSig]
 		HRESULT SetHeadTracking([MarshalAs(UnmanagedType.Bool)] bool bEnableHeadTracking);
 
+		/// <summary>Undocumented</summary>
 		[PreserveSig]
 		HRESULT GetHeadTracking([MarshalAs(UnmanagedType.Bool)] out bool pbEnableHeadTracking);
 
+		/// <summary>Undocumented</summary>
 		[PreserveSig]
 		HRESULT SetRotation(float X, float Y, float Z, float W);
 	}
diff --git a/PInvoke/Ole/Ole32/PropIdl.PROPVARIANT.cs b/PInvoke/Ole/Ole32/PropIdl.PROPVARIANT.cs
index eaf6fc78..600cc8ee 100644
--- a/PInvoke/Ole/Ole32/PropIdl.PROPVARIANT.cs
+++ b/PInvoke/Ole/Ole32/PropIdl.PROPVARIANT.cs
@@ -508,7 +508,7 @@ namespace Vanara.PInvoke
 					return ret | VARTYPE.VT_HRESULT;
 				if (elemtype.IsCOMObject)
 				{
-					var intf = elemtype.GetInterfaces();
+					Type[] intf = elemtype.GetInterfaces();
 					if (intf.Contains(typeof(IStream))) return ret | VARTYPE.VT_STREAM;
 					if (intf.Contains(typeof(IStorage))) return ret | VARTYPE.VT_STORAGE;
 					return ret | VARTYPE.VT_UNKNOWN;
diff --git a/PInvoke/User32/WindowBase.cs b/PInvoke/User32/WindowBase.cs
index 20c68ac1..b92e585d 100644
--- a/PInvoke/User32/WindowBase.cs
+++ b/PInvoke/User32/WindowBase.cs
@@ -341,7 +341,7 @@ public class WindowBase : MarshalByRefObject, IDisposable, IWindowInstance, IWin
 		catch (Exception ex)
 		{
 			if (!OnWndProcException(ex))
-				throw ex;
+				throw;
 			return IntPtr.Zero;
 		}
 		finally
diff --git a/PInvoke/User32/WindowClass.cs b/PInvoke/User32/WindowClass.cs
index 2e14e788..d1469e01 100644
--- a/PInvoke/User32/WindowClass.cs
+++ b/PInvoke/User32/WindowClass.cs
@@ -237,7 +237,7 @@ namespace Vanara.PInvoke
 				{
 					var cp = lParam.ToStructure<CREATESTRUCT>().lpCreateParams;
 					if (cp != IntPtr.Zero && GCHandle.FromIntPtr(cp).Target is IWindowInit wnd)
-						return wnd.InitWndProcOnNCCreate(hwnd, msg, Marshal.GetFunctionPointerForDelegate(wndProc), lParam);
+						return wnd.InitWndProcOnNCCreate(hwnd, msg, Marshal.GetFunctionPointerForDelegate(wndProc ?? throw new NullReferenceException()), lParam);
 				}
 				catch { }
 			}
diff --git a/System/Network/WindowsFirewall.cs b/System/Network/WindowsFirewall.cs
index a9707bfb..8dfbc399 100644
--- a/System/Network/WindowsFirewall.cs
+++ b/System/Network/WindowsFirewall.cs
@@ -322,7 +322,9 @@ public class FirewallProfile
 	/// </remarks>
 	public string[]? ExcludedInterfaces
 	{
+#pragma warning disable CS8619 // Nullability of reference types in value doesn't match target type.
 		get => iPol.ExcludedInterfaces[type] is null ? null : (string[])Array.ConvertAll((object[])iPol.ExcludedInterfaces[type], o => o.ToString());
+#pragma warning restore CS8619 // Nullability of reference types in value doesn't match target type.
 		set => iPol.ExcludedInterfaces[type] = value is null || value.Length == 0 ? null : Array.ConvertAll(value, s => (object)s);
 	}
 
@@ -624,7 +626,9 @@ public class FirewallRule : INamedEntity, IEquatable<FirewallRule>
 	/// </remarks>
 	public string[]? InterfaceNames
 	{
+#pragma warning disable CS8619 // Nullability of reference types in value doesn't match target type.
 		get => iRule.Interfaces is null ? null : (string[])Array.ConvertAll((object[])iRule.Interfaces, o => o.ToString());
+#pragma warning restore CS8619 // Nullability of reference types in value doesn't match target type.
 		set => iRule.Interfaces = value is null || value.Length == 0 ? null : Array.ConvertAll(value, s => (object)s);
 	}
 
@@ -868,12 +872,12 @@ public class FirewallRule : INamedEntity, IEquatable<FirewallRule>
 	private INetFwRule3 iRule3 => iRule as INetFwRule3 ?? throw new NotSupportedException();
 
 	/// <inheritdoc/>
-	public bool Equals(FirewallRule other) => Equals(other.Name, Name) &&
-		Equals(other.Profiles, Profiles) &&
-		Equals(other.Direction, Direction) &&
-		Equals(other.Enabled, Enabled) &&
-		Equals(other.Action, Action) &&
-		Equals(other.ApplicationName, ApplicationName);
+	public bool Equals(FirewallRule? other) => Equals(other?.Name, Name) &&
+		Equals(other?.Profiles, Profiles) &&
+		Equals(other?.Direction, Direction) &&
+		Equals(other?.Enabled, Enabled) &&
+		Equals(other?.Action, Action) &&
+		Equals(other?.ApplicationName, ApplicationName);
 }
 
 /// <summary>Represents the rules for the Windows Firewall.</summary>