diff --git a/src/Windows/Perspex.Win32/Interop/UnmanagedMethods.cs b/src/Windows/Perspex.Win32/Interop/UnmanagedMethods.cs
index 2a0a000226..4d87d0e033 100644
--- a/src/Windows/Perspex.Win32/Interop/UnmanagedMethods.cs
+++ b/src/Windows/Perspex.Win32/Interop/UnmanagedMethods.cs
@@ -703,129 +703,11 @@ namespace Perspex.Win32.Interop
 
             return SetClassLong64(hWnd, nIndex, dwNewLong);
         }
-
-        #region Constants
-
-        public const uint FOS_PICKFOLDERS = 0x00000020;
-        public const uint FOS_FORCEFILESYSTEM = 0x00000040;
-        public const uint FOS_NOVALIDATE = 0x00000100;
-        public const uint FOS_NOTESTFILECREATE = 0x00010000;
-        public const uint FOS_DONTADDTORECENT = 0x02000000;
-
-        public const uint S_OK = 0x0000;
-
-        public const uint SIGDN_FILESYSPATH = 0x80058000;
-
-        #endregion
-
-
-        #region COM
-
+        
         [ComImport, ClassInterface(ClassInterfaceType.None), TypeLibType(TypeLibTypeFlags.FCanCreate), Guid("DC1C5A9C-E88A-4DDE-A5A1-60F82A20AEF7")]
         internal class FileOpenDialogRCW { }
 
-
-        [ComImport(), Guid("42F85136-DB7E-439C-85F1-E4075D135FC8"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
-        internal interface IFileDialog
-        {
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            [PreserveSig()]
-            uint Show([In, Optional] IntPtr hwndOwner); //IModalWindow 
-
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint SetFileTypes([In] uint cFileTypes, [In, MarshalAs(UnmanagedType.LPArray)] IntPtr rgFilterSpec);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint SetFileTypeIndex([In] uint iFileType);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint GetFileTypeIndex(out uint piFileType);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint Advise([In, MarshalAs(UnmanagedType.Interface)] IntPtr pfde, out uint pdwCookie);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint Unadvise([In] uint dwCookie);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint SetOptions([In] uint fos);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint GetOptions(out uint fos);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            void SetDefaultFolder([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint SetFolder([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint GetFolder([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint GetCurrentSelection([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint SetFileName([In, MarshalAs(UnmanagedType.LPWStr)] string pszName);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint GetFileName([MarshalAs(UnmanagedType.LPWStr)] out string pszName);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint SetTitle([In, MarshalAs(UnmanagedType.LPWStr)] string pszTitle);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint SetOkButtonLabel([In, MarshalAs(UnmanagedType.LPWStr)] string pszText);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint SetFileNameLabel([In, MarshalAs(UnmanagedType.LPWStr)] string pszLabel);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint GetResult([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint AddPlace([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi, uint fdap);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint SetDefaultExtension([In, MarshalAs(UnmanagedType.LPWStr)] string pszDefaultExtension);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint Close([MarshalAs(UnmanagedType.Error)] uint hr);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint SetClientGuid([In] ref Guid guid);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint ClearClientData();
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint SetFilter([MarshalAs(UnmanagedType.Interface)] IntPtr pFilter);
-        }
-
-
-        [ComImport, Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
-        internal interface IShellItem
-        {
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint BindToHandler([In] IntPtr pbc, [In] ref Guid rbhid, [In] ref Guid riid, [Out, MarshalAs(UnmanagedType.Interface)] out IntPtr ppvOut);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint GetParent([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint GetDisplayName([In] uint sigdnName, out IntPtr ppszName);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint GetAttributes([In] uint sfgaoMask, out uint psfgaoAttribs);
-
-            [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
-            uint Compare([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi, [In] uint hint, out int piOrder);
-        }
-
-        #endregion
-
-
+        
         [DllImport("shell32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
         internal static extern int SHCreateItemFromParsingName([MarshalAs(UnmanagedType.LPWStr)] string pszPath, IntPtr pbc, ref Guid riid, [MarshalAs(UnmanagedType.Interface)] out IShellItem ppv);
 
@@ -999,6 +881,16 @@ namespace Perspex.Win32.Interop
 
         }
 
+        public enum HRESULT : long
+        {
+            S_FALSE = 0x0001,
+            S_OK = 0x0000,
+            E_INVALIDARG = 0x80070057,
+            E_OUTOFMEMORY = 0x8007000E
+        }
+
+        public const uint SIGDN_FILESYSPATH = 0x80058000;
+
         [Flags]
         internal enum FOS : uint
         {
@@ -1052,4 +944,102 @@ namespace Perspex.Win32.Interop
             public int flagsEx;
         }        
     }
+
+    [ComImport(), Guid("42F85136-DB7E-439C-85F1-E4075D135FC8"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+    internal interface IFileDialog
+    {
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        [PreserveSig()]
+        uint Show([In, Optional] IntPtr hwndOwner); //IModalWindow 
+
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint SetFileTypes([In] uint cFileTypes, [In, MarshalAs(UnmanagedType.LPArray)] IntPtr rgFilterSpec);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint SetFileTypeIndex([In] uint iFileType);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint GetFileTypeIndex(out uint piFileType);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint Advise([In, MarshalAs(UnmanagedType.Interface)] IntPtr pfde, out uint pdwCookie);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint Unadvise([In] uint dwCookie);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint SetOptions([In] uint fos);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint GetOptions(out uint fos);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        void SetDefaultFolder([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint SetFolder([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint GetFolder([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint GetCurrentSelection([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint SetFileName([In, MarshalAs(UnmanagedType.LPWStr)] string pszName);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint GetFileName([MarshalAs(UnmanagedType.LPWStr)] out string pszName);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint SetTitle([In, MarshalAs(UnmanagedType.LPWStr)] string pszTitle);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint SetOkButtonLabel([In, MarshalAs(UnmanagedType.LPWStr)] string pszText);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint SetFileNameLabel([In, MarshalAs(UnmanagedType.LPWStr)] string pszLabel);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint GetResult([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint AddPlace([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi, uint fdap);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint SetDefaultExtension([In, MarshalAs(UnmanagedType.LPWStr)] string pszDefaultExtension);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint Close([MarshalAs(UnmanagedType.Error)] uint hr);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint SetClientGuid([In] ref Guid guid);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint ClearClientData();
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint SetFilter([MarshalAs(UnmanagedType.Interface)] IntPtr pFilter);
+    }
+
+
+    [ComImport, Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+    internal interface IShellItem
+    {
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint BindToHandler([In] IntPtr pbc, [In] ref Guid rbhid, [In] ref Guid riid, [Out, MarshalAs(UnmanagedType.Interface)] out IntPtr ppvOut);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint GetParent([MarshalAs(UnmanagedType.Interface)] out IShellItem ppsi);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint GetDisplayName([In] uint sigdnName, out IntPtr ppszName);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint GetAttributes([In] uint sfgaoMask, out uint psfgaoAttribs);
+
+        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
+        uint Compare([In, MarshalAs(UnmanagedType.Interface)] IShellItem psi, [In] uint hint, out int piOrder);
+    }
 }
diff --git a/src/Windows/Perspex.Win32/SystemDialogImpl.cs b/src/Windows/Perspex.Win32/SystemDialogImpl.cs
index d8473f75c2..84aa78a2a7 100644
--- a/src/Windows/Perspex.Win32/SystemDialogImpl.cs
+++ b/src/Windows/Perspex.Win32/SystemDialogImpl.cs
@@ -136,17 +136,17 @@ namespace Perspex.Win32
                 string result = string.Empty;
 
                 var hWnd = parent?.Handle?.Handle ?? IntPtr.Zero;
-                var frm = (UnmanagedMethods.IFileDialog)(new UnmanagedMethods.FileOpenDialogRCW());
+                var frm = (IFileDialog)(new UnmanagedMethods.FileOpenDialogRCW());
                 uint options;
                 frm.GetOptions(out options);
-                options |= UnmanagedMethods.FOS_PICKFOLDERS | UnmanagedMethods.FOS_FORCEFILESYSTEM | UnmanagedMethods.FOS_NOVALIDATE | UnmanagedMethods.FOS_NOTESTFILECREATE | UnmanagedMethods.FOS_DONTADDTORECENT;
+                options |= (uint)(UnmanagedMethods.FOS.FOS_PICKFOLDERS | UnmanagedMethods.FOS.FOS_FORCEFILESYSTEM | UnmanagedMethods.FOS.FOS_NOVALIDATE | UnmanagedMethods.FOS.FOS_NOTESTFILECREATE | UnmanagedMethods.FOS.FOS_DONTADDTORECENT);
                 frm.SetOptions(options);
 
                 if (dialog.InitialDirectory != null)
                 {
-                    UnmanagedMethods.IShellItem directoryShellItem;
+                    IShellItem directoryShellItem;
                     var riid = new Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE"); //IShellItem
-                    if (UnmanagedMethods.SHCreateItemFromParsingName(dialog.InitialDirectory, IntPtr.Zero, ref riid, out directoryShellItem) == UnmanagedMethods.S_OK)
+                    if (UnmanagedMethods.SHCreateItemFromParsingName(dialog.InitialDirectory, IntPtr.Zero, ref riid, out directoryShellItem) == (uint)UnmanagedMethods.HRESULT.S_OK)
                     {
                         frm.SetFolder(directoryShellItem);
                     }
@@ -154,21 +154,21 @@ namespace Perspex.Win32
 
                 if (dialog.DefaultDirectory != null)
                 {
-                    UnmanagedMethods.IShellItem directoryShellItem;
+                    IShellItem directoryShellItem;
                     var riid = new Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE"); //IShellItem
-                    if (UnmanagedMethods.SHCreateItemFromParsingName(dialog.DefaultDirectory, IntPtr.Zero, ref riid, out directoryShellItem) == UnmanagedMethods.S_OK)
+                    if (UnmanagedMethods.SHCreateItemFromParsingName(dialog.DefaultDirectory, IntPtr.Zero, ref riid, out directoryShellItem) == (uint)UnmanagedMethods.HRESULT.S_OK)
                     {
                         frm.SetDefaultFolder(directoryShellItem);
                     }
                 }
 
-                if (frm.Show(hWnd) == UnmanagedMethods.S_OK)
+                if (frm.Show(hWnd) == (uint)UnmanagedMethods.HRESULT.S_OK)
                 {
-                    UnmanagedMethods.IShellItem shellItem;
-                    if (frm.GetResult(out shellItem) == UnmanagedMethods.S_OK)
+                    IShellItem shellItem;
+                    if (frm.GetResult(out shellItem) == (uint)UnmanagedMethods.HRESULT.S_OK)
                     {
                         IntPtr pszString;
-                        if (shellItem.GetDisplayName(UnmanagedMethods.SIGDN_FILESYSPATH, out pszString) == UnmanagedMethods.S_OK)
+                        if (shellItem.GetDisplayName(UnmanagedMethods.SIGDN_FILESYSPATH, out pszString) == (uint)UnmanagedMethods.HRESULT.S_OK)
                         {
                             if (pszString != IntPtr.Zero)
                             {