diff --git a/src/common.h b/src/common.h
index 70e2409..cbb460c 100644
--- a/src/common.h
+++ b/src/common.h
@@ -10,7 +10,6 @@
 #define SYSTEM3_VERSION "1.4.0"
 
 #include <SDL.h>
-#include <assert.h>
 #include <limits.h>
 #include <stdio.h>
 
diff --git a/src/debugger/debug_info.cpp b/src/debugger/debug_info.cpp
index c969996..e7605e7 100644
--- a/src/debugger/debug_info.cpp
+++ b/src/debugger/debug_info.cpp
@@ -1,6 +1,5 @@
 #include "debugger/debug_info.h"
 #include <algorithm>
-#include <assert.h>
 #include <string.h>
 #include "fileio.h"
 
diff --git a/src/debugger/debugger.cpp b/src/debugger/debugger.cpp
index 758af8c..cbc6da1 100644
--- a/src/debugger/debugger.cpp
+++ b/src/debugger/debugger.cpp
@@ -1,6 +1,7 @@
 #include "debugger/debugger.h"
 #include <algorithm>
 #include <map>
+#include <assert.h>
 #include "common.h"
 #include "nact.h"
 #include "debugger/frontend.h"
diff --git a/src/fileio.h b/src/fileio.h
index 248f388..4ffa1ad 100644
--- a/src/fileio.h
+++ b/src/fileio.h
@@ -33,10 +33,11 @@ public:
 	static int stat_save(const char* filename, struct stat* buf);
 	static std::unique_ptr<FILEIO> open(const char *file_name, int mode);
 	int seek(long offset, int whence) { return fseek(fp, offset, whence); }
+	long tell() { return ftell(fp); }
 	bool read(void* buffer, size_t size) {
 		return fread(buffer, size, 1, fp) == 1;
 	}
-	bool write(void* buffer, size_t size) {
+	bool write(const void* buffer, size_t size) {
 		return fwrite(buffer, size, 1, fp) == 1;
 	}
 	int getc() { return fgetc(fp); }
diff --git a/src/fm/mako_ymfm.cpp b/src/fm/mako_ymfm.cpp
index a0a5efc..8aaf8eb 100644
--- a/src/fm/mako_ymfm.cpp
+++ b/src/fm/mako_ymfm.cpp
@@ -1,5 +1,6 @@
 #include "mako_ymfm.h"
 #include <algorithm>
+#include <assert.h>
 
 const int OPNA_CLOCK = 3993600 * 2;
 
diff --git a/src/sys/ags.cpp b/src/sys/ags.cpp
index aae434a..fa6f76f 100644
--- a/src/sys/ags.cpp
+++ b/src/sys/ags.cpp
@@ -419,6 +419,93 @@ AGS::~AGS()
 	SDL_DestroyTexture(sdlTexture);
 }
 
+void AGS::load(FILEIO* fio)
+{
+	menu_font_size = fio->getw();
+	text_font_size = fio->getw();
+	palette_bank = fio->getw();
+	if (!palette_bank) {
+		palette_bank = -1;
+	}
+	text_font_color = fio->getw();
+	menu_font_color = fio->getw();
+	menu_frame_color = fio->getw();
+	menu_back_color = fio->getw();
+	text_frame_color = fio->getw();
+	text_back_color = fio->getw();
+	for (int i = 0; i < 10; i++) {
+		menu_w[i].sx = fio->getw();
+		menu_w[i].sy = fio->getw();
+		menu_w[i].ex = fio->getw();
+		menu_w[i].ey = fio->getw();
+		menu_w[i].push = fio->getw() ? true : false;
+		menu_w[i].frame = fio->getw() ? true : false;
+		fio->getw();
+		fio->getw();
+
+		if (menu_w[i].screen) {
+			SDL_FreeSurface(menu_w[i].screen);
+		}
+		menu_w[i].screen = NULL;
+		if (menu_w[i].window) {
+			SDL_FreeSurface(menu_w[i].window);
+		}
+		menu_w[i].window = NULL;
+	}
+	for (int i = 0; i < 10; i++) {
+		text_w[i].sx = fio->getw();
+		text_w[i].sy = fio->getw();
+		text_w[i].ex = fio->getw();
+		text_w[i].ey = fio->getw();
+		text_w[i].push = fio->getw() ? true : false;
+		text_w[i].frame = fio->getw() ? true : false;
+		fio->getw();
+		fio->getw();
+
+		if (text_w[i].screen) {
+			SDL_FreeSurface(text_w[i].screen);
+		}
+		text_w[i].screen = NULL;
+		if (text_w[i].window) {
+			SDL_FreeSurface(text_w[i].window);
+		}
+		text_w[i].window = NULL;
+	}
+}
+
+void AGS::save(FILEIO* fio)
+{
+	fio->putw(menu_font_size);
+	fio->putw(text_font_size);
+	fio->putw(palette_bank == -1 ? 0 : palette_bank);
+	fio->putw(text_font_color);
+	fio->putw(menu_font_color);
+	fio->putw(menu_frame_color);
+	fio->putw(menu_back_color);
+	fio->putw(text_frame_color);
+	fio->putw(text_back_color);
+	for (int i = 0; i < 10; i++) {
+		fio->putw(menu_w[i].sx);
+		fio->putw(menu_w[i].sy);
+		fio->putw(menu_w[i].ex);
+		fio->putw(menu_w[i].ey);
+		fio->putw(menu_w[i].push ? 1 : 0);
+		fio->putw(menu_w[i].frame ? 1 : 0);
+		fio->putw(0);
+		fio->putw(0);
+	}
+	for (int i = 0; i < 10; i++) {
+		fio->putw(text_w[i].sx);
+		fio->putw(text_w[i].sy);
+		fio->putw(text_w[i].ex);
+		fio->putw(text_w[i].ey);
+		fio->putw(text_w[i].push ? 1 : 0);
+		fio->putw(text_w[i].frame ? 1 : 0);
+		fio->putw(0);
+		fio->putw(0);
+	}
+}
+
 void AGS::set_cg_file(const char *file_name)
 {
 	bmp_prefix = NULL;
diff --git a/src/sys/ags.h b/src/sys/ags.h
index 7dc049a..6f56184 100644
--- a/src/sys/ags.h
+++ b/src/sys/ags.h
@@ -23,6 +23,7 @@ inline uint32* surface_line(SDL_Surface* surface, int y)
 }
 
 struct Config;
+class FILEIO;
 
 class AGS
 {
@@ -80,6 +81,9 @@ public:
 	AGS(const Config& config, const GameId& game_id);
 	~AGS();
 
+	void load(FILEIO* fio);
+	void save(FILEIO* fio);
+
 	void update_screen();
 
 	void flush_screen(bool update);
diff --git a/src/sys/nact.cpp b/src/sys/nact.cpp
index 3c35e1d..ea63e44 100644
--- a/src/sys/nact.cpp
+++ b/src/sys/nact.cpp
@@ -4,6 +4,7 @@
 	[ NACT ]
 */
 
+#include <assert.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
@@ -562,56 +563,7 @@ bool NACT::load(int index)
 	for (int i = 0; i < 512; i++) {
 		var[i] = fio->getw();
 	}
-	ags->menu_font_size = fio->getw();
-	ags->text_font_size = fio->getw();
-	ags->palette_bank = fio->getw();
-	if (!ags->palette_bank) {
-		ags->palette_bank = -1;
-	}
-	ags->text_font_color = fio->getw();
-	ags->menu_font_color = fio->getw();
-	ags->menu_frame_color = fio->getw();
-	ags->menu_back_color = fio->getw();
-	ags->text_frame_color = fio->getw();
-	ags->text_back_color = fio->getw();
-	for (int i = 0; i < 10; i++) {
-		ags->menu_w[i].sx = fio->getw();
-		ags->menu_w[i].sy = fio->getw();
-		ags->menu_w[i].ex = fio->getw();
-		ags->menu_w[i].ey = fio->getw();
-		ags->menu_w[i].push = fio->getw() ? true : false;
-		ags->menu_w[i].frame = fio->getw() ? true : false;
-		fio->getw();
-		fio->getw();
-
-		if (ags->menu_w[i].screen) {
-			SDL_FreeSurface(ags->menu_w[i].screen);
-		}
-		ags->menu_w[i].screen = NULL;
-		if (ags->menu_w[i].window) {
-			SDL_FreeSurface(ags->menu_w[i].window);
-		}
-		ags->menu_w[i].window = NULL;
-	}
-	for (int i = 0; i < 10; i++) {
-		ags->text_w[i].sx = fio->getw();
-		ags->text_w[i].sy = fio->getw();
-		ags->text_w[i].ex = fio->getw();
-		ags->text_w[i].ey = fio->getw();
-		ags->text_w[i].push = fio->getw() ? true : false;
-		ags->text_w[i].frame = fio->getw() ? true : false;
-		fio->getw();
-		fio->getw();
-
-		if (ags->text_w[i].screen) {
-			SDL_FreeSurface(ags->text_w[i].screen);
-		}
-		ags->text_w[i].screen = NULL;
-		if (ags->text_w[i].window) {
-			SDL_FreeSurface(ags->text_w[i].window);
-		}
-		ags->text_w[i].window = NULL;
-	}
+	ags->load(fio.get());
 	for (int i = 0; i < 10; i++) {
 		fio->read(tvar[i], 22);
 	}
@@ -633,16 +585,6 @@ bool NACT::load(int index)
 	return true;
 }
 
-#define FWRITE(data, size) { \
-	memcpy(&buffer[p], data, size); \
-	p += size; \
-}
-#define FPUTW(data) { \
-	uint16 tmp = (data); \
-	buffer[p++] = tmp & 0xff; \
-	buffer[p++] = (tmp >> 8) & 0xff; \
-}
-
 bool NACT::save(int index, const char header[112])
 {
 	char file_name[_MAX_PATH];
@@ -652,65 +594,34 @@ bool NACT::save(int index, const char header[112])
 	if (!fio)
 		return false;
 
-	uint8 buffer[9510];
-	int p = 0;
-
-	FWRITE(header, 112);
-	FPUTW(sco.page() + 1);
-	FPUTW(0);
-	FPUTW(0);	// cg no?
-	FPUTW(0);
-	FPUTW(mako->current_music);
-	FPUTW(0);
-	FPUTW(sco.current_addr());
-	FPUTW(0);
+	fio->write(header, 112);
+	fio->putw(sco.page() + 1);
+	fio->putw(0);
+	fio->putw(0);	// cg no?
+	fio->putw(0);
+	fio->putw(mako->current_music);
+	fio->putw(0);
+	fio->putw(sco.current_addr());
+	fio->putw(0);
 	for (int i = 0; i < 512; i++) {
-		FPUTW(var[i]);
+		fio->putw(var[i]);
 	}
-	FPUTW(ags->menu_font_size);
-	FPUTW(ags->text_font_size);
-	FPUTW(ags->palette_bank == -1 ? 0 : ags->palette_bank);
-	FPUTW(ags->text_font_color);
-	FPUTW(ags->menu_font_color);
-	FPUTW(ags->menu_frame_color);
-	FPUTW(ags->menu_back_color);
-	FPUTW(ags->text_frame_color);
-	FPUTW(ags->text_back_color);
+	ags->save(fio.get());
 	for (int i = 0; i < 10; i++) {
-		FPUTW(ags->menu_w[i].sx);
-		FPUTW(ags->menu_w[i].sy);
-		FPUTW(ags->menu_w[i].ex);
-		FPUTW(ags->menu_w[i].ey);
-		FPUTW(ags->menu_w[i].push ? 1 : 0);
-		FPUTW(ags->menu_w[i].frame ? 1 : 0);
-		FPUTW(0);
-		FPUTW(0);
-	}
-	for (int i = 0; i < 10; i++) {
-		FPUTW(ags->text_w[i].sx);
-		FPUTW(ags->text_w[i].sy);
-		FPUTW(ags->text_w[i].ex);
-		FPUTW(ags->text_w[i].ey);
-		FPUTW(ags->text_w[i].push ? 1 : 0);
-		FPUTW(ags->text_w[i].frame ? 1 : 0);
-		FPUTW(0);
-		FPUTW(0);
-	}
-	for (int i = 0; i < 10; i++) {
-		FWRITE(tvar[i], 22);
+		fio->write(tvar[i], 22);
 	}
 	for (int i = 0; i < 30; i++) {
 		for (int j = 0; j < 10; j++) {
-			FWRITE(tvar_stack[i][j], 22);
+			fio->write(tvar_stack[i][j], 22);
 		}
 	}
 	for (int i = 0; i < 30; i++) {
 		for (int j = 0; j < 20; j++) {
-			FPUTW(var_stack[i][j]);
+			fio->putw(var_stack[i][j]);
 		}
 	}
 
-	fio->write(buffer, 9510);
+	assert(fio->tell() == 9510);
 	return true;
 }