diff --git a/README.md b/README.md
index 124c4bf..2d82978 100644
--- a/README.md
+++ b/README.md
@@ -55,6 +55,9 @@ track.
 By default, system3-sdl2 uses MIDI sound if available. This option forces FM
 tone generator emulation.
 
+#### `-fullscreen`
+Starts the game in fullscreen mode.
+
 #### `-mididevice` _number_
 Specifies the MIDI device number to use. If not specified, the first available
 device is used.
diff --git a/src/config.cpp b/src/config.cpp
index 6be2a5a..257cfb0 100644
--- a/src/config.cpp
+++ b/src/config.cpp
@@ -154,6 +154,8 @@ Config::Config(int argc, char *argv[])
 			title = argv[++i];
 		else if (strcmp(argv[i], "-scanline") == 0)
 			scanline = true;
+		else if (strcmp(argv[i], "-fullscreen") == 0)
+			fullscreen = true;
 #ifdef ENABLE_DEBUGGER
 		else if (strcmp(argv[i], "-debugger") == 0)
 			debugger_mode = parse_debugger_mode(argv[++i]);
@@ -224,6 +226,8 @@ void Config::load_ini()
 				title = val;
 			else if (!strcasecmp(key, "scanline"))
 				scanline = to_bool(val, lineno);
+			else if (!strcasecmp(key, "fullscreen"))
+				fullscreen = to_bool(val, lineno);
 #ifdef ENABLE_DEBUGGER
 			else if (!strcasecmp(key, "debugger"))
 				debugger_mode = parse_debugger_mode(val, lineno);
diff --git a/src/config.h b/src/config.h
index 0947742..f7bdb0d 100644
--- a/src/config.h
+++ b/src/config.h
@@ -47,6 +47,7 @@ struct Config {
 	bool use_fm = false;
 	bool no_antialias = false;
 	bool scanline = false;
+	bool fullscreen = false;
 	TexthookMode texthook_mode = TexthookMode::NONE;
 	DebuggerMode debugger_mode = DebuggerMode::DISABLED;
 	std::string texthook_suppressions;
diff --git a/src/sdlmain.cpp b/src/sdlmain.cpp
index 9d30558..6f71979 100644
--- a/src/sdlmain.cpp
+++ b/src/sdlmain.cpp
@@ -25,7 +25,7 @@ std::unique_ptr<NACT> g_nact;
 
 namespace {
 
-SDL_Window* create_window(const GameId& game_id)
+SDL_Window* create_window(const Config& config, const GameId& game_id)
 {
 	std::string title = "System3-sdl2 " SYSTEM3_VERSION;
 	if (game_id.title) {
@@ -48,7 +48,7 @@ SDL_Window* create_window(const GameId& game_id)
 	SDL_SetHint(SDL_HINT_ORIENTATIONS, "LandscapeLeft LandscapeRight");
 	Uint32 flags = SDL_WINDOW_FULLSCREEN;
 #else
-	Uint32 flags = SDL_WINDOW_RESIZABLE;
+	Uint32 flags = config.fullscreen ? SDL_WINDOW_FULLSCREEN_DESKTOP : SDL_WINDOW_RESIZABLE;
 #endif
 
 #ifdef __EMSCRIPTEN__
@@ -76,7 +76,7 @@ int main(int argc, char *argv[])
 	}
 	GameId game_id(config);
 
-	g_window = create_window(game_id);
+	g_window = create_window(config, game_id);
 	g_renderer = SDL_CreateRenderer(g_window, -1, 0);
 	sdl_custom_event_type = SDL_RegisterEvents(1);
 
diff --git a/system3.ini.example b/system3.ini.example
index 531f753..ec7748b 100644
--- a/system3.ini.example
+++ b/system3.ini.example
@@ -21,6 +21,9 @@ playlist = bgm/playlist.txt
 ; Force FM tone generator emulation even if MIDI is available.
 fm = true
 
+; If set to true, the game starts in fullscreen mode.
+;fullscreen = true
+
 ; MIDI device number to use for music playback.
 mididevice = 0