diff --git a/gui/Utilities/CPU/CPUCapabilities.cs b/gui/Utilities/CPU/CPUCapabilities.cs
index 948a6ef..4b9a24a 100644
--- a/gui/Utilities/CPU/CPUCapabilities.cs
+++ b/gui/Utilities/CPU/CPUCapabilities.cs
@@ -325,9 +325,9 @@ namespace com.muldersoft.slunkcrypt.gui.utils.cpu
 
         private static class Internal
         {
-            const string DLL_NAME_X86 = "cpu-capabilities-x86.dll";
-            const string DLL_NAME_X64 = "cpu-capabilities-x64.dll";
-            const string DLL_KERNEL32 = "kernel32.dll";
+            private const string DLL_NAME_X86 = "cpu-capabilities-x86.dll";
+            private const string DLL_NAME_X64 = "cpu-capabilities-x64.dll";
+            private const string DLL_KERNEL32 = "kernel32.dll";
 
             /* GetCPUArchitecture() */
             [DllImport(DLL_NAME_X64, CallingConvention = CallingConvention.Cdecl)]
@@ -372,9 +372,9 @@ namespace com.muldersoft.slunkcrypt.gui.utils.cpu
             public static extern uint GetCPULibraryVersionX86();
 
             /* IsWow64Process2() */
-            [DllImport(DLL_KERNEL32, SetLastError = true)]
+            [DllImport(DLL_KERNEL32, EntryPoint = "IsWow64Process2", ExactSpelling = true)]
             public static extern bool IsWow64Process2(IntPtr process, out ushort processMachine, out ushort nativeMachine);
-            [DllImport(DLL_KERNEL32)]
+            [DllImport(DLL_KERNEL32, EntryPoint = "GetCurrentProcess", ExactSpelling = true)]
             public static extern IntPtr GetCurrentProcess();
         }
 
diff --git a/gui/Utilities/SystemMenu.cs b/gui/Utilities/SystemMenu.cs
index 401e721..ed148ea 100644
--- a/gui/Utilities/SystemMenu.cs
+++ b/gui/Utilities/SystemMenu.cs
@@ -160,6 +160,8 @@ namespace com.muldersoft.slunkcrypt.gui.utils
 
         private class Native
         {
+            private const string DLL_USER32 = "user32.dll";
+
             [Flags]
             public enum MenuFlags : uint
             {
@@ -171,13 +173,13 @@ namespace com.muldersoft.slunkcrypt.gui.utils
                 MF_SEPARATOR  = 0x0800
             }
 
-            [DllImport("user32.dll")]
+            [DllImport(DLL_USER32, CharSet = CharSet.Unicode, EntryPoint = "GetSystemMenu", ExactSpelling = true)]
             public static extern IntPtr GetSystemMenu(IntPtr hWnd, bool bRevert);
 
-            [DllImport("user32.dll", CharSet = CharSet.Auto)]
+            [DllImport(DLL_USER32, CharSet = CharSet.Unicode, EntryPoint = "AppendMenuW", ExactSpelling = true)]
             public static extern bool AppendMenu(IntPtr hMenu, MenuFlags uFlags, UIntPtr uIDNewItem, string lpNewItem);
 
-            [DllImport("user32.dll")]
+            [DllImport(DLL_USER32, CharSet = CharSet.Unicode, EntryPoint = "ModifyMenuW", ExactSpelling = true)]
             public static extern bool ModifyMenu(IntPtr hMenu, uint uPosition, MenuFlags uFlags, UIntPtr uIDNewItem, string lpNewItem);
         }
     }
diff --git a/gui/Utilities/WindowHelper.cs b/gui/Utilities/WindowHelper.cs
index 48d65f0..36f68a9 100644
--- a/gui/Utilities/WindowHelper.cs
+++ b/gui/Utilities/WindowHelper.cs
@@ -35,14 +35,14 @@ namespace com.muldersoft.slunkcrypt.gui.utils
             if (!ReferenceEquals(window, null))
             {
                 const int GWL_STYLE = -16;
-                const uint WS_MAXIMIZEBOX = 0x10000;
+                const ulong WS_MAXIMIZEBOX = 0x10000;
                 try
                 {
                     WindowInteropHelper interopHelper = new WindowInteropHelper(window);
-                    uint value = NativeMethods.GetWindowLong(interopHelper.Handle, GWL_STYLE);
-                    if ((value & WS_MAXIMIZEBOX) != 0U)
+                    ulong value = NativeMethods.GetWindowLongPtr(interopHelper.Handle, GWL_STYLE);
+                    if (value != 0UL)
                     {
-                        NativeMethods.SetWindowLong(interopHelper.Handle, GWL_STYLE, value & (~WS_MAXIMIZEBOX));
+                        NativeMethods.SetWindowLongPtr(interopHelper.Handle, GWL_STYLE, value & (~WS_MAXIMIZEBOX));
                     }
                 }
                 catch { }
@@ -51,17 +51,49 @@ namespace com.muldersoft.slunkcrypt.gui.utils
 
         private static class NativeMethods
         {
-            [DllImport("user32.dll", SetLastError = true)]
+            private const string DLL_USER32 = "user32.dll";
+
+            [DllImport(DLL_USER32, CharSet = CharSet.Unicode, EntryPoint = "BringWindowToTop", ExactSpelling = true)]
             public static extern bool BringWindowToTop(IntPtr hWnd);
 
-            [DllImport("user32.dll", SetLastError = true)]
+            [DllImport(DLL_USER32, CharSet = CharSet.Unicode, EntryPoint = "SetForegroundWindow", ExactSpelling = true)]
             public static extern bool SetForegroundWindow(IntPtr hWnd);
 
-            [DllImport("user32.dll", SetLastError = true)]
-            public static extern uint GetWindowLong(IntPtr hWnd, int nIndex);
+            [DllImport(DLL_USER32, CharSet = CharSet.Unicode, EntryPoint = "GetWindowLongW", ExactSpelling = true)]
+            private static extern UIntPtr GetWindowLongPtr32(IntPtr hWnd, int nIndex);
 
-            [DllImport("user32.dll", SetLastError = true)]
-            public static extern uint SetWindowLong(IntPtr hWnd, int nIndex, uint dwNewLong);
+            [DllImport(DLL_USER32, CharSet = CharSet.Unicode, EntryPoint = "GetWindowLongPtrW", ExactSpelling = true)]
+            private static extern UIntPtr GetWindowLongPtr64(IntPtr hWnd, int nIndex);
+
+            [DllImport(DLL_USER32, CharSet = CharSet.Unicode, EntryPoint = "SetWindowLongW", ExactSpelling = true)]
+            private static extern UIntPtr SetWindowLongPtr32(IntPtr hWnd, int nIndex, UIntPtr dwNewLong);
+
+            [DllImport(DLL_USER32, CharSet = CharSet.Unicode, EntryPoint = "SetWindowLongPtrW", ExactSpelling = true)]
+            private static extern UIntPtr SetWindowLongPtr64(IntPtr hWnd, int nIndex, UIntPtr dwNewLong);
+
+            public static ulong GetWindowLongPtr(IntPtr hWnd, int nIndex)
+            {
+                if (IntPtr.Size >= 8)
+                {
+                    return GetWindowLongPtr64(hWnd, nIndex).ToUInt64();
+                }
+                else
+                {
+                    return GetWindowLongPtr32(hWnd, nIndex).ToUInt64();
+                }
+            }
+
+            public static void SetWindowLongPtr(IntPtr hWnd, int nIndex, ulong dwNewLong)
+            {
+                if (IntPtr.Size >= 8)
+                {
+                    SetWindowLongPtr64(hWnd, nIndex, new UIntPtr(dwNewLong));
+                }
+                else
+                {
+                    SetWindowLongPtr32(hWnd, nIndex, new UIntPtr(dwNewLong));
+                }
+            }
         }
     }
 }