diff --git a/Source/NotifyIconWpf/Interop/WinApi.cs b/Source/NotifyIconWpf/Interop/WinApi.cs
index e0d61ba..2cb96ea 100644
--- a/Source/NotifyIconWpf/Interop/WinApi.cs
+++ b/Source/NotifyIconWpf/Interop/WinApi.cs
@@ -21,15 +21,15 @@ namespace Hardcodet.Wpf.TaskbarNotification.Interop
     [DllImport("USER32.DLL", EntryPoint = "CreateWindowExW", SetLastError = true)]
     public static extern IntPtr CreateWindowEx(int dwExStyle, [MarshalAs(UnmanagedType.LPWStr)] string lpClassName,
                            [MarshalAs(UnmanagedType.LPWStr)] string lpWindowName, int dwStyle, int x, int y,
-                           int nWidth, int nHeight, uint hWndParent, int hMenu, int hInstance,
-                           int lpParam);
+                           int nWidth, int nHeight, IntPtr hWndParent, IntPtr hMenu, IntPtr hInstance,
+                           IntPtr lpParam);
 
 
     /// <summary>
     /// Processes a default windows procedure.
     /// </summary>
     [DllImport("USER32.DLL")]
-    public static extern long DefWindowProc(IntPtr hWnd, uint msg, uint wparam, uint lparam);
+    public static extern IntPtr DefWindowProc(IntPtr hWnd, uint msg, IntPtr wparam, IntPtr lparam);
     
     /// <summary>
     /// Registers the helper window class.
diff --git a/Source/NotifyIconWpf/Interop/WindowClass.cs b/Source/NotifyIconWpf/Interop/WindowClass.cs
index e4f625a..bfc42f7 100644
--- a/Source/NotifyIconWpf/Interop/WindowClass.cs
+++ b/Source/NotifyIconWpf/Interop/WindowClass.cs
@@ -7,7 +7,7 @@ namespace Hardcodet.Wpf.TaskbarNotification.Interop
   /// Callback delegate which is used by the Windows API to
   /// submit window messages.
   /// </summary>
-  public delegate long WindowProcedureHandler(IntPtr hwnd, uint uMsg, uint wparam, uint lparam);
+  public delegate IntPtr WindowProcedureHandler(IntPtr hwnd, uint uMsg, IntPtr wparam, IntPtr lparam);
 
 
   /// <summary>
diff --git a/Source/NotifyIconWpf/Interop/WindowMessageSink.cs b/Source/NotifyIconWpf/Interop/WindowMessageSink.cs
index 3c696f9..42fd3a9 100644
--- a/Source/NotifyIconWpf/Interop/WindowMessageSink.cs
+++ b/Source/NotifyIconWpf/Interop/WindowMessageSink.cs
@@ -187,14 +187,14 @@ namespace Hardcodet.Wpf.TaskbarNotification.Interop
       taskbarRestartMessageId = WinApi.RegisterWindowMessage("TaskbarCreated");
 
       // Create the message window
-      MessageWindowHandle = WinApi.CreateWindowEx(0, WindowId, "", 0, 0, 0, 1, 1, 0, 0, 0, 0);
+      MessageWindowHandle = WinApi.CreateWindowEx(0, WindowId, "", 0, 0, 0, 1, 1, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero);
 
       if (MessageWindowHandle == IntPtr.Zero)
       {
 #if SILVERLIGHT
       	throw new Exception("Message window handle was not a valid pointer.");
 #else
-        throw new Win32Exception();
+        throw new Win32Exception("Message window handle was not a valid pointer");
 #endif
       }
     }
@@ -207,7 +207,7 @@ namespace Hardcodet.Wpf.TaskbarNotification.Interop
     /// <summary>
     /// Callback method that receives messages from the taskbar area.
     /// </summary>
-    private long OnWindowMessageReceived(IntPtr hwnd, uint messageId, uint wparam, uint lparam)
+    private IntPtr OnWindowMessageReceived(IntPtr hwnd, uint messageId, IntPtr wparam, IntPtr lparam)
     {
       if (messageId == taskbarRestartMessageId)
       {
@@ -231,15 +231,14 @@ namespace Hardcodet.Wpf.TaskbarNotification.Interop
     /// or higher, this parameter can be used to resolve mouse coordinates.
     /// Currently not in use.</param>
     /// <param name="lParam">Provides information about the event.</param>
-    private void ProcessWindowMessage(uint msg, uint wParam, uint lParam)
+    private void ProcessWindowMessage(uint msg, IntPtr wParam, IntPtr lParam)
     {
       if (msg != CallbackMessageId) return;
 
-      switch (lParam)
+      switch (lParam.ToInt32())
       {
         case 0x200:
-          MouseEventReceived(MouseEvent.MouseMove);
-          break;
+          MouseEventReceived(MouseEvent.MouseMove);          break;
 
         case 0x201:
           MouseEventReceived(MouseEvent.IconLeftMouseDown);