diff --git a/manual/customize.rst b/manual/customize.rst
index 0229e5451a..bd5206bf04 100644
--- a/manual/customize.rst
+++ b/manual/customize.rst
@@ -49,7 +49,7 @@ Environment variables
       the system theme -- beware of crashes and hangs.
     * ``CALIBRE_SHOW_DEPRECATION_WARNINGS`` - causes calibre to print deprecation warnings to stdout. Useful for calibre developers.
     * ``CALIBRE_NO_DEFAULT_PROGRAMS`` - prevent calibre from automatically registering the filetypes it is capable of handling with Windows.
-    * ``CALIBRE_USE_DARK_PALETTE`` - set it to ``1`` to have calibre use dark colors and ``0`` for light colors. Works on **Linux only**.
+    * ``CALIBRE_USE_DARK_PALETTE`` - set it to ``1`` to have calibre use dark colors and ``0`` for light colors. Overrides the system-wide dark setting. When set, changes to the colors while calibre is running will not take effect. Works on **Linux and Windows only**.
     * ``SYSFS_PATH`` - Use if sysfs is mounted somewhere other than /sys
     * ``http_proxy``, ``https_proxy`` - used on Linux to specify an HTTP(S) proxy
 
diff --git a/src/calibre/gui2/__init__.py b/src/calibre/gui2/__init__.py
index 4bc9f641f3..a15f926884 100644
--- a/src/calibre/gui2/__init__.py
+++ b/src/calibre/gui2/__init__.py
@@ -1229,7 +1229,10 @@ class Application(QApplication):
             using_calibre_style = True
         if using_calibre_style:
             if iswindows:
-                use_dark_palette = windows_is_system_dark_mode_enabled()
+                if 'CALIBRE_USE_DARK_PALETTE' in os.environ:
+                    use_dark_palette = os.environ.get('CALIBRE_USE_DARK_PALETTE') == '1'
+                else:
+                    use_dark_palette = windows_is_system_dark_mode_enabled()
             elif ismacos:
                 use_dark_palette = False
             else:
@@ -1257,6 +1260,8 @@ class Application(QApplication):
         @pyqtSlot(str, str, QDBusVariant)
         def linux_desktop_setting_changed(self, namespace, key, val):
             if (namespace, key) == ('org.freedesktop.appearance', 'color-scheme'):
+                if 'CALIBRE_USE_DARK_PALETTE' in os.environ:
+                    return
                 use_dark_palette = val.variant() == 1
                 if use_dark_palette != bool(self.is_dark_theme):
                     if use_dark_palette:
@@ -1266,6 +1271,8 @@ class Application(QApplication):
                 self.on_palette_change()
 
     def check_for_windows_palette_change(self):
+        if 'CALIBRE_USE_DARK_PALETTE' in os.environ:
+            return
         use_dark_palette = bool(windows_is_system_dark_mode_enabled())
         if bool(self.is_dark_theme) != use_dark_palette:
             if use_dark_palette: