diff --git a/PInvoke/ActiveDS/IADs.Interface2.cs b/PInvoke/ActiveDS/IADs.Interface2.cs
index 96af6e203..634442574 100644
--- a/PInvoke/ActiveDS/IADs.Interface2.cs
+++ b/PInvoke/ActiveDS/IADs.Interface2.cs
@@ -1545,7 +1545,7 @@ int LowPart
 	/// <summary>Converts interface values to <see cref="Int64"/>.</summary>
 	/// <param name="li">The <see cref="IADsLargeInteger"/> instance.</param>
 	/// <returns>A <see cref="long"/> value.</returns>
-	public static long ToInt64(this IADsLargeInteger li) => Macros.MAKELONG64(unchecked((uint)li.LowPart), li.HighPart);
+	public static long ToInt64(this IADsLargeInteger li) => Macros.MAKELONG64(li.LowPart, li.HighPart);
 
 	/// <summary>
 	/// <para>
diff --git a/PInvoke/Shared/WinUser/Macros.cs b/PInvoke/Shared/WinUser/Macros.cs
index 4b9789469..e54f03944 100644
--- a/PInvoke/Shared/WinUser/Macros.cs
+++ b/PInvoke/Shared/WinUser/Macros.cs
@@ -112,6 +112,12 @@ public static long ALIGN_TO_MULTIPLE(long value, int pow2) =>
 	/// <returns>The return value is a LONG value.</returns>
 	public static uint MAKELONG(IConvertible wLow, IConvertible wHigh) => (wHigh.ToUInt32(null) << 16) | (wLow.ToUInt32(null) & 0xffff);
 
+	/// <summary>Creates a LONG64 value by concatenating the specified values.</summary>
+	/// <param name="dwLow">The low-order double word of the new value.</param>
+	/// <param name="dwHigh">The high-order double word of the new value.</param>
+	/// <returns>The return value is a LONG64 value.</returns>
+	public static long MAKELONG64(IConvertible dwLow, int dwHigh) => ((long)dwHigh << 32) | (dwLow.ToInt64(null) & 0xffffffff);
+
 	/// <summary>Creates a LONG64 value by concatenating the specified values.</summary>
 	/// <param name="dwLow">The low-order double word of the new value.</param>
 	/// <param name="dwHigh">The high-order double word of the new value.</param>