diff --git a/src/fileio.cpp b/src/fileio.cpp
index 99d2f17..d442b59 100644
--- a/src/fileio.cpp
+++ b/src/fileio.cpp
@@ -6,6 +6,8 @@
 
 #include "fileio.h"
 
+_TCHAR g_root[_MAX_PATH];
+
 FILEIO::FILEIO()
 {
 	// 初期化
@@ -20,25 +22,28 @@ FILEIO::~FILEIO(void)
 	}
 }
 
-bool FILEIO::Fopen(_TCHAR *filename, int mode)
+bool FILEIO::Fopen(const _TCHAR *filename, int mode)
 {
+	_TCHAR path[_MAX_PATH];
+	_stprintf_s(path, _MAX_PATH, _T("%s%s"), filename, g_root);
+
 	if(fp != NULL) {
 		Fclose();
 	}
 	fp = NULL;
 	
 	if(mode == FILEIO_READ_BINARY) {
-		fp = fopen(filename, _T("rb"));
+		fp = fopen(path, _T("rb"));
 	} else if(mode == FILEIO_WRITE_BINARY) {
-		fp = fopen(filename, _T("wb"));
+		fp = fopen(path, _T("wb"));
 	} else if(mode == FILEIO_READ_WRITE_BINARY) {
-		fp = fopen(filename, _T("r+b"));
+		fp = fopen(path, _T("r+b"));
 	} else if(mode == FILEIO_READ_ASCII) {
-		fp = fopen(filename, _T("r"));
+		fp = fopen(path, _T("r"));
 	} else if(mode == FILEIO_WRITE_ASCII) {
-		fp = fopen(filename, _T("w"));
+		fp = fopen(path, _T("w"));
 	} else if(mode == FILEIO_READ_WRITE_ASCII) {
-		fp = fopen(filename, _T("r+w"));
+		fp = fopen(path, _T("r+w"));
 	}
 	return (fp != NULL);
 }
diff --git a/src/fileio.h b/src/fileio.h
index 37d994a..363c76d 100644
--- a/src/fileio.h
+++ b/src/fileio.h
@@ -29,7 +29,7 @@ public:
 	FILEIO();
 	~FILEIO();
 
-	bool Fopen(_TCHAR *filename, int mode);
+	bool Fopen(const _TCHAR *filename, int mode);
 	void Fclose();
 	uint32 Fseek(long offset, int origin);
 	uint32 Ftell();
diff --git a/src/sdlmain.cpp b/src/sdlmain.cpp
index d3ee81e..bc4c198 100644
--- a/src/sdlmain.cpp
+++ b/src/sdlmain.cpp
@@ -5,7 +5,6 @@ extern "C" {
 	void ags_setAntialiasedStringMode(int on);
 }
 
-_TCHAR g_root[_MAX_PATH];
 SDL_Window* g_window;
 
 int main(int argc, char *argv[])
diff --git a/src/sys/ags.cpp b/src/sys/ags.cpp
index 834e651..3a8cfa6 100644
--- a/src/sys/ags.cpp
+++ b/src/sys/ags.cpp
@@ -8,7 +8,6 @@
 #include "crc32.h"
 #include "../fileio.h"
 
-extern _TCHAR g_root[_MAX_PATH];
 extern SDL_Window* g_window;
 
 #define SET_TEXT(n, x1, y1, x2, y2, f) { \
@@ -76,10 +75,7 @@ AGS::AGS(NACT* parent) : nact(parent)
 	memset(gaiji, 0, sizeof(gaiji));
 
 	FILEIO* fio = new FILEIO();
-	_TCHAR file_path[_MAX_PATH];
-	_stprintf_s(file_path, _MAX_PATH, _T("%sGAIJI.DAT"), g_root);
-
-	if(fio->Fopen(file_path, FILEIO_READ_BINARY)) {
+	if(fio->Fopen(_T("GAIJI.DAT"), FILEIO_READ_BINARY)) {
 		int d1, d2;
 		while((d1 = fio->Fgetc()) != EOF) {
 			d2 = fio->Fgetc();
diff --git a/src/sys/dri.cpp b/src/sys/dri.cpp
index 7169b0e..b2dd9e1 100644
--- a/src/sys/dri.cpp
+++ b/src/sys/dri.cpp
@@ -8,20 +8,17 @@
 #include "crc32.h"
 #include "../fileio.h"
 
-extern _TCHAR g_root[_MAX_PATH];
-
 uint8* DRI::load(_TCHAR path[], int page, int* size)
 {
-	_TCHAR base_path[_MAX_PATH], file_path[_MAX_PATH];
+	_TCHAR base_path[_MAX_PATH];
 	_tcscpy_s(base_path, _MAX_PATH, path);
 
 	FILEIO* fio = new FILEIO();
 
 	// ページの位置を取得
 	base_path[0] = _T('A');
-	_stprintf_s(file_path, _MAX_PATH, _T("%s%s"), g_root, base_path);
 
-	if(!fio->Fopen(file_path, FILEIO_READ_BINARY)) {
+	if(!fio->Fopen(base_path, FILEIO_READ_BINARY)) {
 		delete fio;
 		return NULL;
 	}
@@ -52,9 +49,8 @@ uint8* DRI::load(_TCHAR path[], int page, int* size)
 	// A??.DAT以外にリンクされている場合はファイルを開き直す
 	if(disk_index != 1) {
 		base_path[0] = _T('A') + disk_index - 1;
-		_stprintf_s(file_path, _MAX_PATH, _T("%s%s"), g_root, base_path);
 		fio->Fclose();
-		if(!fio->Fopen(file_path, FILEIO_READ_BINARY)) {
+		if(!fio->Fopen(base_path, FILEIO_READ_BINARY)) {
 			delete fio;
 			return NULL;
 		}
diff --git a/src/sys/nact.cpp b/src/sys/nact.cpp
index f3bf142..bc343db 100644
--- a/src/sys/nact.cpp
+++ b/src/sys/nact.cpp
@@ -10,8 +10,6 @@
 #include "dri.h"
 #include "../fileio.h"
 
-extern _TCHAR g_root[_MAX_PATH];
-
 // 初期化
 
 NACT::NACT()
@@ -28,10 +26,7 @@ NACT::NACT()
 
 	// AG00.DAT読み込み
 	FILEIO* fio = new FILEIO();
-	_TCHAR file_path[_MAX_PATH];
-	_stprintf_s(file_path, _MAX_PATH, _T("%sAG00.DAT"), g_root);
-
-	if(fio->Fopen(file_path, FILEIO_READ_BINARY)) {
+	if(fio->Fopen(_T("AG00.DAT"), FILEIO_READ_BINARY)) {
 		int d0, d1, d2, d3;
 		char string[MAX_CAPTION];
 		fio->Fgets(string);
diff --git a/src/sys/nact_crc32.cpp b/src/sys/nact_crc32.cpp
index e11d07c..fb7afbe 100644
--- a/src/sys/nact_crc32.cpp
+++ b/src/sys/nact_crc32.cpp
@@ -8,17 +8,11 @@
 #include "crc32.h"
 #include "../fileio.h"
 
-extern _TCHAR g_root[_MAX_PATH];
-
 uint32 NACT::calc_crc32()
 {
 	uint32 crc = 0;
 	FILEIO* fio = new FILEIO();
-
-	_TCHAR file_path[_MAX_PATH];
-	_stprintf_s(file_path, _MAX_PATH, _T("%sADISK.DAT"), g_root);
-
-	if(fio->Fopen(file_path, FILEIO_READ_BINARY)) {
+	if(fio->Fopen(_T("ADISK.DAT"), FILEIO_READ_BINARY)) {
 		uint32 table[256];
 		for(int i = 0; i < 256; i++) {
 			uint32 c = i;
@@ -43,9 +37,7 @@ uint32 NACT::calc_crc32()
 #if defined(_SYSTEM2)
 	if(crc == CRC32_SDPS) {
 		// Super D.P.S縺ｮ蝣ｴ蜷医�ｯBDISK.DAT縺ｮCRC繧貞叙繧�
-		_stprintf_s(file_path, _MAX_PATH, _T("%sBDISK.DAT"), g_root);
-		
-		if(fio->Fopen(file_path, FILEIO_READ_BINARY)) {
+		if(fio->Fopen(_T("BDISK.DAT"), FILEIO_READ_BINARY)) {
 			uint32 table[256];
 			for(int i = 0; i < 256; i++) {
 				uint32 c = i;
diff --git a/src/sys/nact_sys1.cpp b/src/sys/nact_sys1.cpp
index 810093c..6b4b3f8 100644
--- a/src/sys/nact_sys1.cpp
+++ b/src/sys/nact_sys1.cpp
@@ -67,7 +67,6 @@
 	} \
 }
 
-extern _TCHAR g_root[_MAX_PATH];
 extern HWND g_hwnd;
 
 void NACT::opening()
@@ -953,13 +952,12 @@ void NACT::cmd_l()
 
 	if(1 <= index && index <= 26) {
 		// ASLEEP_A.DAT - ASLEEP_Z.DAT
-		_TCHAR path[_MAX_PATH], file_path[_MAX_PATH];
+		_TCHAR path[_MAX_PATH];
 		_tcscpy_s(path, _MAX_PATH, _T("ASLEEP_A.DAT"));
 		path[7] = _T('A') + index - 1;
-		_stprintf_s(file_path, _MAX_PATH, _T("%s%s"), g_root, path);
 
 		FILEIO* fio = new FILEIO();
-		if(fio->Fopen(file_path, FILEIO_READ_BINARY)) {
+		if(fio->Fopen(path, FILEIO_READ_BINARY)) {
 			fio->Fseek(112, FILEIO_SEEK_SET);
 
 			int next_page = fio->Fgetw() - 1;
@@ -1108,13 +1106,12 @@ void NACT::cmd_q()
 
 	if(1 <= index && index <= 26) {
 		// ASLEEP_A.DAT - ASLEEP_Z.DAT
-		_TCHAR path[_MAX_PATH], file_path[_MAX_PATH];
+		_TCHAR path[_MAX_PATH];
 		_tcscpy_s(path, _MAX_PATH, _T("ASLEEP_A.DAT"));
 		path[7] = _T('A') + index - 1;
-		_stprintf_s(file_path, _MAX_PATH, _T("%s%s"), g_root, path);
 
 		FILEIO* fio = new FILEIO();
-		if(fio->Fopen(file_path, FILEIO_WRITE_BINARY)) {
+		if(fio->Fopen(path, FILEIO_WRITE_BINARY)) {
 			uint8 buffer[9510];
 			int p = 0;
 
diff --git a/src/sys/nact_sys2.cpp b/src/sys/nact_sys2.cpp
index be0a4ab..81eb9da 100644
--- a/src/sys/nact_sys2.cpp
+++ b/src/sys/nact_sys2.cpp
@@ -55,7 +55,6 @@
 	} \
 }
 
-extern _TCHAR g_root[_MAX_PATH];
 extern HWND g_hwnd;
 
 void NACT::cmd_calc()
@@ -1024,13 +1023,12 @@ void NACT::cmd_l()
 
 	if(1 <= index && index <= 26) {
 		// ASLEEP_A.DAT - ASLEEP_Z.DAT
-		_TCHAR path[_MAX_PATH], file_path[_MAX_PATH];
+		_TCHAR path[_MAX_PATH];
 		_tcscpy_s(path, _MAX_PATH, _T("ASLEEP_A.DAT"));
 		path[7] = _T('A') + index - 1;
-		_stprintf_s(file_path, _MAX_PATH, _T("%s%s"), g_root, path);
 
 		FILEIO* fio = new FILEIO();
-		if(fio->Fopen(file_path, FILEIO_READ_BINARY)) {
+		if(fio->Fopen(path, FILEIO_READ_BINARY)) {
 			fio->Fseek(112, FILEIO_SEEK_SET);
 
 			int next_page = fio->Fgetw() - 1;
@@ -1221,13 +1219,12 @@ void NACT::cmd_q()
 
 	if(1 <= index && index <= 26) {
 		// ASLEEP_A.DAT - ASLEEP_Z.DAT
-		_TCHAR path[_MAX_PATH], file_path[_MAX_PATH];
+		_TCHAR path[_MAX_PATH];
 		_tcscpy_s(path, _MAX_PATH, _T("ASLEEP_A.DAT"));
 		path[7] = _T('A') + index - 1;
-		_stprintf_s(file_path, _MAX_PATH, _T("%s%s"), g_root, path);
 
 		FILEIO* fio = new FILEIO();
-		if(fio->Fopen(file_path, FILEIO_WRITE_BINARY)) {
+		if(fio->Fopen(path, FILEIO_WRITE_BINARY)) {
 			uint8 buffer[9510];
 			int p = 0;
 
diff --git a/src/sys/nact_sys3.cpp b/src/sys/nact_sys3.cpp
index afae9ed..69cb3ae 100644
--- a/src/sys/nact_sys3.cpp
+++ b/src/sys/nact_sys3.cpp
@@ -919,11 +919,8 @@ void NACT::cmd_l()
 
 	if(index == 0) {
 		// 特殊セーブ
-		_TCHAR file_path[_MAX_PATH];
-		_stprintf_s(file_path, _MAX_PATH, _T("%sASLEEP.DAT"), g_root);
-
 		FILEIO* fio = new FILEIO();
-		if(fio->Fopen(file_path, FILEIO_READ_BINARY)) {
+		if(fio->Fopen(_T("ASLEEP.DAT"), FILEIO_READ_BINARY)) {
 			// U01 - U20
 			for(int i = 21; i <= 40; i++) {
 				var[i] = fio->Fgetw();
@@ -937,13 +934,12 @@ void NACT::cmd_l()
 		delete fio;
 	} else if(1 <= index && index <= 26) {
 		// ASLEEP_A.DAT - ASLEEP_Z.DAT
-		_TCHAR path[_MAX_PATH], file_path[_MAX_PATH];
+		_TCHAR path[_MAX_PATH];
 		_tcscpy_s(path, _MAX_PATH, _T("ASLEEP_A.DAT"));
 		path[7] = _T('A') + index - 1;
-		_stprintf_s(file_path, _MAX_PATH, _T("%s%s"), g_root, path);
 
 		FILEIO* fio = new FILEIO();
-		if(fio->Fopen(file_path, FILEIO_READ_BINARY)) {
+		if(fio->Fopen(path, FILEIO_READ_BINARY)) {
 			fio->Fseek(112, FILEIO_SEEK_SET);
 
 			int next_page = fio->Fgetw() - 1;
@@ -1031,13 +1027,12 @@ void NACT::cmd_l()
 		delete fio;
 	} else if(101 <= index && index <= 126) {
 		// ASLEEP_A.DAT - ASLEEP_Z.DAT
-		_TCHAR path[_MAX_PATH], file_path[_MAX_PATH];
+		_TCHAR path[_MAX_PATH];
 		_tcscpy_s(path, _MAX_PATH, _T("ASLEEP_A.DAT"));
 		path[7] = _T('A') + index - 101;
-		_stprintf_s(file_path, _MAX_PATH, _T("%s%s"), g_root, path);
 
 		FILEIO* fio = new FILEIO();
-		if(fio->Fopen(file_path, FILEIO_READ_BINARY)) {
+		if(fio->Fopen(path, FILEIO_READ_BINARY)) {
 			fio->Fseek(112 + 16, FILEIO_SEEK_SET);
 			var[0] = fio->Fgetw();
 			fio->Fclose();
@@ -1211,11 +1206,8 @@ void NACT::cmd_q()
 
 	if(index == 0) {
 		// 特殊セーブ
-		_TCHAR file_path[_MAX_PATH];
-		_stprintf_s(file_path, _MAX_PATH, _T("%sASLEEP.DAT"), g_root);
-
 		FILEIO* fio = new FILEIO();
-		if(fio->Fopen(file_path, FILEIO_WRITE_BINARY)) {
+		if(fio->Fopen(_T("ASLEEP.DAT"), FILEIO_WRITE_BINARY)) {
 			// U01 - U20
 			for(int i = 21; i <= 40; i++) {
 				fio->Fputw(var[i]);
@@ -1229,13 +1221,12 @@ void NACT::cmd_q()
 		delete fio;
 	} else if(1 <= index && index <= 26) {
 		// ASLEEP_A.DAT - ASLEEP_Z.DAT
-		_TCHAR path[_MAX_PATH], file_path[_MAX_PATH];
+		_TCHAR path[_MAX_PATH];
 		_tcscpy_s(path, _MAX_PATH, _T("ASLEEP_A.DAT"));
 		path[7] = _T('A') + index - 1;
-		_stprintf_s(file_path, _MAX_PATH, _T("%s%s"), g_root, path);
 
 		FILEIO* fio = new FILEIO();
-		if(fio->Fopen(file_path, FILEIO_WRITE_BINARY)) {
+		if(fio->Fopen(path, FILEIO_WRITE_BINARY)) {
 			uint8 buffer[9510];
 			int p = 0;