diff --git a/port/linux/src/sdl_platform.c b/port/linux/src/sdl_platform.c
index 7384b6040d..55d47e378f 100644
--- a/port/linux/src/sdl_platform.c
+++ b/port/linux/src/sdl_platform.c
@@ -21,6 +21,10 @@ and the debug keyboard that the game's console reads.
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#ifdef HALO_WINDOWS
+/* port/windows/src/win32_window.c, compiled with the Windows SDK */
+void win32_window_borderless_apply(SDL_Window *window);
+#endif
 #if !defined(_WIN32) && !defined(HALO_ANDROID)
 #include <signal.h>
 #endif
@@ -839,6 +843,9 @@ BOOL platform_video_initialize(unsigned long width, unsigned long height)
 #endif
 	platform_fullscreen_requested = platform_fullscreen_setting();
 	platform_fullscreen_kind_apply();
+#endif
+#ifdef HALO_WINDOWS
+	win32_window_borderless_apply(platform_window);
 #endif
 	platform_gl_context = SDL_GL_CreateContext(platform_window);
 #ifdef HALO_GLES
@@ -950,6 +957,11 @@ void platform_video_swap(void)
 	static Uint64 next_frame;
 	Uint64 interval, now;
 
+#endif
+#ifdef HALO_WINDOWS
+	/* SDL can restore its fullscreen styles on a mode or focus change.
+	Keep borderless on the desktop before the driver presents a frame. */
+	win32_window_borderless_apply(platform_window);
 #endif
 	SDL_GL_SwapWindow(platform_window);
 #ifdef HALO_WEB
diff --git a/port/windows/src/win32_window.c b/port/windows/src/win32_window.c
new file mode 100644
index 0000000000..e038765a62
--- /dev/null
+++ b/port/windows/src/win32_window.c
@@ -0,0 +1,28 @@
+/*
+WIN32_WINDOW.C
+
+Keep borderless OpenGL windows on the desktop. NVIDIA's driver treats
+SDL's WS_POPUP fullscreen window as exclusive even without a display mode,
+which blanks the monitor when the player switches to another application.
+*/
+
+#include <windows.h>
+#include <SDL3/SDL.h>
+
+void win32_window_borderless_apply(SDL_Window *window)
+{
+	HWND handle;
+	LONG_PTR style;
+
+	if (!(SDL_GetWindowFlags(window) & SDL_WINDOW_FULLSCREEN) || SDL_GetWindowFullscreenMode(window))
+		return;
+	handle = SDL_GetPointerProperty(SDL_GetWindowProperties(window), SDL_PROP_WINDOW_WIN32_HWND_POINTER, NULL);
+	if (!handle)
+		return;
+	style = GetWindowLongPtr(handle, GWL_STYLE);
+	if (!(style & WS_POPUP) && !(GetWindowLongPtr(handle, GWL_EXSTYLE) & WS_EX_TOPMOST))
+		return;
+	SetWindowLongPtr(handle, GWL_STYLE, style & ~WS_POPUP);
+	SetWindowPos(handle, HWND_NOTOPMOST, 0, 0, 0, 0,
+		SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE | SWP_FRAMECHANGED);
+}