diff --git a/PInvoke/DwmApi/DwmApi.cs b/PInvoke/DwmApi/DwmApi.cs
index 99a2781e..22a9577e 100644
--- a/PInvoke/DwmApi/DwmApi.cs
+++ b/PInvoke/DwmApi/DwmApi.cs
@@ -599,7 +599,7 @@ public static partial class DwmApi
 	/// <returns>If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.</returns>
 	[DllImport(Lib.DwmApi, SetLastError = false, ExactSpelling = true)]
 	[PInvokeData("dwmapi.h")]
-	public static extern HRESULT DwmGetCompositionTimingInfo(HWND hwnd, ref DWM_TIMING_INFO dwAttribute);
+	public static extern HRESULT DwmGetCompositionTimingInfo([Optional] HWND hwnd, ref DWM_TIMING_INFO dwAttribute);
 
 	/// <summary>Retrieves transport attributes.</summary>
 	/// <param name="pfIsRemoting">
@@ -827,12 +827,12 @@ public static partial class DwmApi
 	/// </param>
 	/// <returns>If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.</returns>
 	[PInvokeData("dwmapi.h")]
-	public static HRESULT DwmSetWindowAttribute<T>(HWND hwnd, DWMWINDOWATTRIBUTE dwAttribute, [In] T pvAttribute)
+	public static HRESULT DwmSetWindowAttribute<T>(HWND hwnd, DWMWINDOWATTRIBUTE dwAttribute, [In] T? pvAttribute)
 	{
 		if (pvAttribute == null || !CorrespondingTypeAttribute.CanSet(dwAttribute, typeof(T))) throw new ArgumentException();
 		var attr = pvAttribute is bool ? Convert.ToUInt32(pvAttribute) : (pvAttribute.GetType().IsEnum ? Convert.ChangeType(pvAttribute, Enum.GetUnderlyingType(pvAttribute.GetType())) : pvAttribute);
-		using (var p = new PinnedObject(attr))
-			return DwmSetWindowAttribute(hwnd, dwAttribute, p, Marshal.SizeOf(attr));
+		using var p = new PinnedObject(attr);
+		return DwmSetWindowAttribute(hwnd, dwAttribute, p, Marshal.SizeOf(attr));
 	}
 
 	/// <summary>
@@ -1236,7 +1236,7 @@ public static partial class DwmApi
 		{
 			int RotateLeft(int value, int nBits)
 			{
-				nBits = nBits % 0x20;
+				nBits %= 0x20;
 				return (value << nBits) | (value >> (0x20 - nBits));
 			}
 			return cxLeftWidth ^ RotateLeft(cyTopHeight, 8) ^ RotateLeft(cxRightWidth, 0x10) ^ RotateLeft(cyBottomHeight, 0x18);
diff --git a/UnitTests/PInvoke/DwmApi/DwmApi.csproj b/UnitTests/PInvoke/DwmApi/DwmApi.csproj
index 5b0bfb22..efe28f61 100644
--- a/UnitTests/PInvoke/DwmApi/DwmApi.csproj
+++ b/UnitTests/PInvoke/DwmApi/DwmApi.csproj
@@ -1,6 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <AssemblyName>UnitTest.PInvoke.DwmApi</AssemblyName>
+    <TargetFramework>$(TargetFramework)-windows</TargetFramework>
+    <UseWindowsForms>true</UseWindowsForms>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System.Windows.Forms" />
diff --git a/UnitTests/PInvoke/DwmApi/DwmApiTests.cs b/UnitTests/PInvoke/DwmApi/DwmApiTests.cs
index 67fa486a..d2d002f0 100644
--- a/UnitTests/PInvoke/DwmApi/DwmApiTests.cs
+++ b/UnitTests/PInvoke/DwmApi/DwmApiTests.cs
@@ -1,6 +1,7 @@
 using NUnit.Framework;
 using System.Drawing;
 using System.Threading;
+using System.Windows.Forms;
 using static Vanara.PInvoke.DwmApi;
 
 namespace Vanara.PInvoke.Tests;