From 2d4b424dbd818b3baf1551a37c0669ae910a4abf Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 2 Feb 2022 08:35:47 +0530
Subject: [PATCH] Dont attempt to read NULL MSG.lParam

---
 src/calibre/gui2/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/calibre/gui2/__init__.py b/src/calibre/gui2/__init__.py
index 6f8a898f7c..9facf6188b 100644
--- a/src/calibre/gui2/__init__.py
+++ b/src/calibre/gui2/__init__.py
@@ -1621,7 +1621,7 @@ def nativeEventFilter(self, eventType, message):
             if eventType == b"windows_generic_MSG":
                 msg = ctypes.wintypes.MSG.from_address(message.__int__())
                 # https://docs.microsoft.com/en-us/windows/win32/winmsg/wm-settingchange
-                if msg.message == 0x001A:  # WM_SETTINGCHANGE
+                if msg.message == 0x001A and msg.lParam:  # WM_SETTINGCHANGE
                     if ctypes.wstring_at(msg.lParam) == 'ImmersiveColorSet':
                         QApplication.instance().check_for_windows_palette_change()
                         # prevent Qt from handling this event