diff --git a/win/rfb_win32/WMShatter.h b/win/rfb_win32/WMShatter.h
new file mode 100644
index 0000000..3ea63b1
--- /dev/null
+++ b/win/rfb_win32/WMShatter.h
@@ -0,0 +1,50 @@
+/* Copyright (C) 2002-2005 RealVNC Ltd.  All Rights Reserved.
+ * 
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+
+// -=- WMShatter.h
+//
+// WMShatter provides the IsSafeWM routine, which returns true iff the
+// supplied window message is safe to pass to DispatchMessage, or to
+// process in the window procedure.
+//
+// This is only required, of course, to avoid so-called "shatter" attacks
+// to be made against the VNC server, which take advantage of the noddy
+// design of the Win32 window messaging system.
+//
+// The API here is designed to hopefully be future proof, so that if they
+// ever come up with a proper way to determine whether a message is safe
+// or not then it can just be reimplemented here...
+
+#ifndef __RFB_WIN32_SHATTER_H__
+#define __RFB_WIN32_SHATTER_H__
+
+#include <windows.h>
+
+namespace rfb {
+  namespace win32 {
+
+    bool IsSafeWM(HWND window, UINT msg, WPARAM wParam, LPARAM lParam);
+
+    LRESULT SafeDefWindowProc(HWND wnd, UINT msg, WPARAM wParam, LPARAM lParam);
+
+    LRESULT SafeDispatchMessage(const MSG* msg);
+
+  };
+};
+
+#endif // __RFB_WIN32_SHATTER_H__