diff --git a/src/sdlmain.cpp b/src/sdlmain.cpp
index 69ad134..c3c05c4 100644
--- a/src/sdlmain.cpp
+++ b/src/sdlmain.cpp
@@ -90,11 +90,11 @@ int main(int argc, char *argv[])
 	EM_ASM( xsystem35.shell.windowSizeChanged(); );
 #endif
 
-	bool restart = true;
-	while (restart) {
-		restart = g_nact->mainloop();
+	int exit_code = NACT_RESTART;
+	while (exit_code == NACT_RESTART) {
+		exit_code = g_nact->mainloop();
 		delete g_nact;
-		if (restart)
+		if (exit_code == NACT_RESTART)
 			g_nact = NACT::create(config);
 	}
 
@@ -106,7 +106,7 @@ int main(int argc, char *argv[])
 	romfsExit();
 #endif
 
-    return 0;
+    return exit_code;
 }
 
 #ifdef __EMSCRIPTEN__
@@ -115,7 +115,7 @@ extern "C"
 EMSCRIPTEN_KEEPALIVE
 void sys_restart()
 {
-	g_nact->quit(true);
+	g_nact->quit(NACT_RESTART);
 }
 
 #endif
diff --git a/src/sys/nact.cpp b/src/sys/nact.cpp
index f598b1f..2cb27b8 100644
--- a/src/sys/nact.cpp
+++ b/src/sys/nact.cpp
@@ -109,7 +109,6 @@ NACT::NACT(int sys_ver, uint32 crc32_a, uint32 crc32_b, const Config& config)
 	}
 
 	terminate = false;
-	restart_after_terminate = false;
 }
 
 NACT::~NACT()
@@ -126,7 +125,7 @@ NACT::~NACT()
 	platform_finalize();
 }
 
-bool NACT::mainloop()
+int NACT::mainloop()
 {
 	msgskip->load_from_file();
 
@@ -138,13 +137,17 @@ bool NACT::mainloop()
 			sys_sleep(10);
 		}
 	}
-	return restart_after_terminate;
+	while (exit_code == NACT_HALT) {
+		// exit_code can change if the user selects restart or exit from the menu.
+		sys_sleep(16);
+	}
+	return exit_code;
 }
 
-void NACT::quit(bool restart)
+void NACT::quit(int code)
 {
+	exit_code = code;
 	terminate = true;
-	restart_after_terminate = restart;
 }
 
 // コマンドパーサ
@@ -155,14 +158,6 @@ void NACT::execute()
 	// アドレスの確認
 	if(scenario_addr < 2 || scenario_addr >= scenario_size) {
 		fatal("Scenario error");
-	}
-
-	// 致命的なエラー発生 or 正常終了
-	if(fatal_error) {
-		if(!post_quit) {
-			quit(false);
-		}
-		post_quit = true;
 		return;
 	}
 
@@ -563,7 +558,7 @@ void NACT::fatal(const char* format, ...) {
 	vsnprintf(buf, sizeof buf, format, args);
 	SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Fatal Error: %s", buf);
 	SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "system3", buf, g_window);
-	fatal_error = true;
+	quit(0);
 }
 
 NACT* NACT::create(const Config& config) {
diff --git a/src/sys/nact.h b/src/sys/nact.h
index 1c6a26d..819fb4c 100644
--- a/src/sys/nact.h
+++ b/src/sys/nact.h
@@ -90,6 +90,10 @@ enum Language {
 	ENGLISH = 1,
 };
 
+// special codes for NACT::exit_code
+const int NACT_HALT = -1;
+const int NACT_RESTART = -2;
+
 class NACT
 {
 public:
@@ -106,9 +110,6 @@ protected:
 	void execute();
 	void load_scenario(int page);
 
-	bool fatal_error = false;
-	bool post_quit = false;
-
 	// ADISK.DAT, ASLEEP.DAT
 	char adisk[16];
 
@@ -245,16 +246,16 @@ protected:
 
 	// 終了フラグ
 	bool terminate;
-	bool restart_after_terminate;
+	int exit_code;
 
 	// Platform-specific setup / cleanup code
 	void platform_initialize();
 	void platform_finalize();
 
 public:
-	bool mainloop();
+	int mainloop();
 	void sys_sleep(int ms);
-	void quit(bool restart);
+	void quit(int code);
 
 	int get_screen_height();
 
diff --git a/src/sys/nact_input.cpp b/src/sys/nact_input.cpp
index b8c9b32..82a7bf9 100644
--- a/src/sys/nact_input.cpp
+++ b/src/sys/nact_input.cpp
@@ -32,7 +32,7 @@ void NACT::pump_events()
 
 		switch (e.type) {
 		case SDL_QUIT:
-			quit(false);
+			quit(0);
 			break;
 
 		case SDL_WINDOWEVENT:
diff --git a/src/sys/nact_sys1.cpp b/src/sys/nact_sys1.cpp
index 06b0a52..5a2196b 100644
--- a/src/sys/nact_sys1.cpp
+++ b/src/sys/nact_sys1.cpp
@@ -1017,8 +1017,7 @@ void NACT_Sys1::cmd_y()
 				break;
 			case 2:
 				if(param == 0) {
-					post_quit = true;
-					fatal_error = true;
+					quit(NACT_HALT);
 				} else {
 					WAIT(100)
 				}
@@ -1027,8 +1026,7 @@ void NACT_Sys1::cmd_y()
 				WAIT(param * 1000)
 				break;
 			case 255:
-				post_quit = true;
-				fatal_error = true;
+				quit(NACT_HALT);
 				break;
 		}
 	} else if (crc32_a == CRC32_GAKUEN || crc32_a == CRC32_GAKUEN_ENG) {
@@ -1154,19 +1152,17 @@ void NACT_Sys1::cmd_y()
 				ags->draw_hankaku = (param == 1) ? true : false;
 				break;
 			case 253:
-				post_quit = false;
-				fatal_error = true;
+				quit(0);
 				break;
 			case 254:
 				RND = 0;
 				break;
 			case 255:
 				if(crc32_a == CRC32_DPS || crc32_a == CRC32_DPS_SG || crc32_a == CRC32_DPS_SG2 || crc32_a == CRC32_DPS_SG3) {
-					post_quit = false;
+					quit(0);
 				} else {
-					post_quit = true;
+					quit(NACT_HALT);
 				}
-				fatal_error = true;
 				break;
 		}
 	}
diff --git a/src/sys/nact_sys2.cpp b/src/sys/nact_sys2.cpp
index 81c4d70..70dba0d 100644
--- a/src/sys/nact_sys2.cpp
+++ b/src/sys/nact_sys2.cpp
@@ -1242,8 +1242,7 @@ void NACT_Sys2::cmd_y()
 			RND = 0;
 			break;
 		case 255:
-			post_quit = (param == 1) ? true : false;
-			fatal_error = true;
+			quit(param == 1 ? NACT_HALT : 0);
 			break;
 	}
 // Y1
diff --git a/src/sys/nact_sys3.cpp b/src/sys/nact_sys3.cpp
index 87592fc..f816040 100644
--- a/src/sys/nact_sys3.cpp
+++ b/src/sys/nact_sys3.cpp
@@ -1402,8 +1402,7 @@ void NACT_Sys3::cmd_y()
 			RND = (crc32_a == CRC32_YAKATA3_CD || crc32_a == CRC32_YAKATA3_FD || crc32_a == CRC32_NINGYO) ? 1 : 0;
 			break;
 		case 255:
-			post_quit = (param == 1) ? true : false;
-			fatal_error = true;
+			quit(param == 1 ? NACT_HALT : 0);
 			break;
 	}
 }
diff --git a/src/win/nact_win.cpp b/src/win/nact_win.cpp
index 353551f..14e5aa7 100644
--- a/src/win/nact_win.cpp
+++ b/src/win/nact_win.cpp
@@ -177,10 +177,10 @@ bool NACT::handle_platform_event(const SDL_Event& e)
 			save_screenshot(ags);
 			break;
 		case ID_RESTART:
-			quit(true);
+			quit(NACT_RESTART);
 			break;
 		case ID_EXIT:
-			quit(false);
+			quit(0);
 			break;
 		case ID_SCREEN_WINDOW:
 			SDL_SetWindowFullscreen(g_window, 0);